Hey, so Ive been researching this for a while now and am looking for some input as my knowledge and experiences are limited. I have an 85 f150 single cab long bed with a 300 and 4 speed overdrive and 2.47 rear gears with an intake and 4 barrel. 1st and second have been whining for a while now and 3rd just recently started as well. This was my daily for weekly 3-4 hour trips so I liked the highway gears for the MPG, but Im thinking I might retire it to a weekend toy and use it for towing a small camper or pontoon boat. I wanted a zf5 for a long time, but have had a ton of trouble finding a 2wd small block example in decent condition, and Ive been told that it wouldnt be a good match for my rear gear. So this led me to look into the t19 since 1st is synchronized and I will most likely be using it quite a bit. I spoke briefly with AbandonedBronco about this, but he said his knowledge was more on the 4wd and not the 2wd. Is it possible to find a wide ratio t19 that I can bolt to my 300? Is it easier to find a different variation? Do you think having that low 1st gear is enough to tow maybe 5k-6k lbs even with my rear end? Would it be a direct swap assuming I could get a driveshaft and crossmember from a donor truck? Is there a different Transmission that would be easier to find and install? Id rather not swap out the rear as I recently rebuilt it, so Im hoping someone has some more insight for me. Thanks in advance!

 

Ya know, I watched three small block 2wd ZF5's get hauled to the crusher a couple years ago. They were in F350's at the local junkyard in old bread trucks with 300's. I figured somebody would have snagged them, but they would be a bit of an odd duck in a 2wd half ton.

 

Ive been visiting different local yards every couple weeks looking for one, but all I find is the 4 speeds from the 80-88 and the M5OD. Im now thinking I might have to give up the overdrive because I dont know if the 5 speeds 1st gear is low enough for me to tow anything of value besides my little 16 foot boat

 

I looked up your 4 speed and the 4th gear has a .81 ratio with a 3.39 1st. The zf 5th gear is .76 with a 5.72 1st gear. So to me, the zf would be even better, giving you what you have now with your 4 speed overdrive while also giving you that low 5.72 1st gear. If you are towing, you do not need to use 5th gear overdrive, you could leave it in 4th which is 1 to 1 like the 4 speeds. But one of the old 4 speeds would be cheaper to buy and maybe easier to find, since all you need is the trans, you should be able to reuse your old 4 speed od bellhousing.

 

Yea I would have thought a zf5 would have been ideal, but I was having a low vacuum at cruise issue that AbandonedBronco said could be because in OD its lugging the motor too much since I was only getting like 8-9" at cruising. I found some defects in my carbs casting, so I sent it back and am hoping that is the issue. Assuming it is, I might consider the zf again, but with how cheap and plentiful these 4 speeds are I figured I should at least consider them. Do you think that 5.72 1st gear would be enough to pull a 20-24ft camper with my rear end? Or do you think Id have to look at the NP435 or T19/T18 wide ratios for the 6.xx 1st gear?

 

5.72 maybe more useable, the 6.32 is not a road gear but a off-road crawling gear. That is a good question, not sure what would be best. But while you still have your 4 speed overdrive in your truck, if you want to experiment with how the engine runs and the vacuum levels, all you have to do is leave the 4 speed overdrive in 3rd gear. 3rd gear in the that trans is 1 to 1. No different from 4th gear in the t18 and t19 transmissions which are 1 to 1 in 4th. So you can see exactly what you will end up with without the overdrive gear by just leaving the trans you have now in 3rd and do some driving with it.

 

Yea I've been doing that for the past 2 or 3 weeks and it's been working fine. I'm not used to it reving so high on the highway, but im sure I'll get used to it. The vacuum seems to he a bit better in terms of cruising, but that was only at 55, im not sure how it will be closer to 70 or 75. I'm waiting on a replacement carb from Edelbrock, so I'll have to try that when it comes in.

As far as the 6.xx gear, I know it's an offroad gear for most, but do you think the 2.47 rear might make it closer to 2nd with like a 3.55 or 4.10 rear? My current setup makes it barely possible to tow my 1200lb boat, so I just want to make sure towing closer to 5k will be fine

 

What you have now in 1st is 3.39 to 1 with a 2.47 to 1 rear. So your final ratio from the engine to the rear wheels is 8.37 to 1 That is 3.39 x 2.47 = 8.37

With a t18 or t19 in first gear it has a 6.32 ratio. With your 2.47 rear the final ratio in 1st will be 6.32 x 2.47 = 15.61

If you had a 4.10 gear with the transmission you have now, 3.39 x 4.10 = 13.89 So the 6.32 gear is still steeper than having a 4.10 rearend.

 

Okay so that would be perfect for towing a little more weight then? And I've heard the wide ratio t-19s are tougher to find, but the close ratio came behind the 460 and diesels right?

 

What rear axle is in the truck? I do not see anything higher than 3.08 for the 8.8 or 3.00 for a 9”

 

8.8 with 2.47 gears

 

Here is the list for 1985.

non-removable carrier (8.8" ring gear), 2.47 ratio
non-removable carrier (8.8" ring gear), 2.73 ratio
non-removable carrier (8.8" ring gear), 3.08 ratio
non-removable carrier (8.8" ring gear), 3.55 ratio
non-removable carrier (8.8" ring gear), 4.10 ratio
removable carrier (9" ring gear), 2.47 ratio
removable carrier (9" ring gear), 2.75 ratio
removable carrier (9" ring gear), 3.00 ratio
removable carrier (9" ring gear), 3.25 ratio
removable carrier (9" ring gear), 3.50 ratio
removable carrier (9" ring gear), 4.11 ratio

 

According to this, all the t19's had a milder 1st gear that was synchronized with a 1st gear in the 4's, except a couple of years they made a wide ratio unit with 1st gear in the 5's. The 4x4 t19's did have a 1st gear in the 6's.

https://www.novak-adapt.com/knowledg...manual/t18-t19

 

Oh so all 2wd T-19s had 1st gear in the 4's? So it will only be a bit better than my current 1st then. I guess if I wanted a lower gear id have to look at the np435 or T18 I guess and just give up the synchronized 1st and reverse.

 

According to that website the most common t19 had a 4.02 1st gear. 4.02 x 2.47 would give you a final ratio in 1st of 9.93. Little bit better than what you have now.

Whatever you get, with that very low 2.47 gear it's going to be a little weird. I don't know what your plans are for getting another transmission, but if you got a later 80's truck that has a 5 speed and a higher ratio rearend that you can swap in at the same time, that would put your truck back to a more "normal" setup with low enough gears to tow and a overdrive for fuel mileage. Getting a donor with the same wheelbase would guarantee you had the driveshaft and anything else you needed for the swap.

Here are the transmissions available in 1985.

MT, 4 speed, New Process manufactured, 4x4
MT, 4 speed, Warner manufactured, 4x2, 12" extension
MT, 4 speed, Warner manufactured, 4x2, 4" extension
MT, 4 speed, New Process manufactured, 4x2, 4-1/4" extension
MT, 3 speed
AT, 4x2, C6
MT, 4 speed, New Process manufactured, 4x2, 12-1/4" extension
AT, 4x2, AOD transmission, 8-302 (5.0L), 10-1/4" extension housing
AT, 4x2, AOD transmission, 8-302 (5.0L), 11-1/4" extension housing
AT, 4x2, AOD transmission, 6-300 (4.9L)
AT, 4x2, C5
MT, 4 speed, Ford (Overdrive) manufactured, 4x2
MT, 4 speed, Ford (Overdrive) manufactured, 4x4
MT, 4 speed, Warner manufactured, 4x4
AT, 4x4, AOD (8-302, 5.0L)
AT, 4x4, C6

I picked a New process with a 4 1/4" extension and saw one in Pa for $400. I picked the New Process with the 12 1/4" extension and got a lot more hits and selection in Pa. Got a lot of hits with both Warner 4 speeds, and they are about the same price.