I have a 1976 f-250 4X4 with a 390 and 4 speed transmission, is there any overdrive transmitions that can be bolted to my 390?

 

One solution and possibly the best, would be to put an overdrive module on your existing tranny.

 

Thanks for your responce, but what is an overdrive module?

 

Look up gear vendors or US Gear. Maybe check in the back of any truck magazine.
http://www.gearvendors.com/index.html

The units are very expensive and really will not pay for themselves with gas savings. Occasionally one will be available on eBay but they often go for big $$ there also.

 

Thanks for the info.

 

Yup, like $2500 or so...

I will have one on all my oldies once I become a millionaire.

heh heh.

 

Because of the divorced transfer case, the gearvendor module won't fit on a automatic tranny. You would have to change the transfer case location or just change the whole setup and make it a married system. I am looking into options for my 77F250 4x4. An adapter plate is made to bolt up an AOD tranny to the 390 and it runs around $795. An AOD was made for the 302, so you may have to upgrade to perfomance parts which can be expensive. The stock AOD may not hold up to the 390. Or another option would be to install a 5 speed into your truck instead of an automatic. I am putting in a 521 stroker into my truck so I have been looking into the overdrive as well, but all the options I have looked into would cost me at least 3500 bucks. So, I may just change my axle ratio to 3.54 gears, install a C-6, and put 35 inch tires on to gain as much as possible. See how that goes. I haven't found many articles on people actually installing overdrive tranny's on a 460, 400, 390 to see how it works.

 

he says he has a 4 speed, which i think is the problem, i dont think there is a manual tranny with o/d that will bolt up to an FE, but i am not much into manual tranny swaps with different bell housings mating to newer o/d trannies

I have just given up on all the "try to do it cheap" better fuel mileage tricks and just use another vehicle for better mileage when the big boy isnt needed

 

Is there a 5 speed manual that will bolt in place of a NP 435? Would it bolt to my current bell housing?

I'm running 4.10 gears with a 390 and 435 in my dually truck and it turns at scary RPM above 60 mph...

 

you could just get taller tires stocks are what about 32-33 inchs tall 35s are about 10% taller and will lower your final ratio to about the same as an OD tranny.

 

An OD is usually 20-30%. It is tough to get any real change with tires. Wider tires get worse gas mileage also. If the present tires are good then it is tough to pay for the new ones with non-existent savings.

 

Ford used an overdrive trans in late '70s cars, vans and pick-ups. It was called a "3+1". Was based on the Top Loader 4 speed. Do not confuse this with the SROD overdrive used in Mustangs of the same vintage. The 3+1 is all cast iron and looks like a regular Top Loader. Ths SROD has the shifter integral with the tailhousing.
The 3+1 will bolt to your FE bell housing and will require a shorter intermediate shaft to the transfer case. It has a fairly low 1st gear, though no where as low as the granny in your truck. Third is direct, same as fourth in your rig, and fourth is about a 28% overdrive.
These transmissions are fairly easy to find in the Pacific Northwest, and not too expensive.
I have had one in my 66 F-100 for about 10 years with no trouble. Had one in a 68 F-250 4X4 before that. If you don't mind giving up the granny gear it might be the way to go.
Good luck,
Roger Carter

 

Thanks all, I will be looking for that 3+1 mister Carter.

Thanks agian,
John

 

how creative are you. How about a 5th over drive? The purests will probabbly argue this will not work. I drove one in a 1968. Yes the 68 and 76 are different beasts. According to my date the transmissions stayed the same through this model change.. Yea, the 68 trans bolted up diffeent than the 76. The 68 had a mount on the bell while the newer trucks had a cross member. (easy mod)
I have done alot of reasearch on this topic. I am not a pro though.

The owner of the 68 ford f350 took a Clark 5 speed and switched around two gears in the train and converted it to a 5th over drive. The shifting pattern changes when this is done.
This tranny comes out of the bigger trucks. it bolted right up to the 68.

I haven't given up on this idea. I am not quite ready for the trans to go into the frame so I put it on the back burner.

I would love to get a discussion going on this topic and figuire out exactly how to accomplish it in a 73 to 79.

 

Boy am I glad you guy's are picking up on the OD tranny need. Ive decided to go with the M5OD in my 76. Don't panic. It's going behind a 300 Six with a carb. I do have some juice clutch issues that need to be worked out. The tranny is from a 92 f-150 300-6 and my 4-speed is a linkage connected boat anchor. This is really great having other of knowledge on tap. Go FTE.