Just got through installing a ZF 6 speed in my 97 OBS.
I shortened my rear shaft by 13 inches and lengthen the front 13.

I decided to change the rear shaft to a one piece since it was shortened so much, that also let me do away with the carrier bearing. (nice added feature)

I used the original ZF 6 cooling lines also. I had to replace my radiator this spring and the replacement had cooler fittings for an automatic transmission so I just hooked the ZF lines to them.

Some on here had said the transmission wouldn't fit and would hit the floor pan. I didn't have this problem. The shifter tower is at the original place and the engine inclination is still the same place.

I did fab a new cross member from 2 x 2 x 1/4 square tubing and used the factory trans mount.

I am going to have to add some 4 degree spring wedges the rear end to turn the pinion down some, It goes from smooth to a vibration under slight acceleration and smooth again under heavy acceleration. I guess its going from slight down pinion to 0 (vibration from being totally straight) and then going slightly up under hard power.

I did this swap because my ZF 5 speed had a ton of gear roll over noise (400,000 miles) and with 3.55 gears and a 4.14 first gear ratio (came out of an IDI truck, I didn't know they were different when I bought the truck with a bad trans and put that one in. It was impossible to start off in high side with my backhoe on my goose neck on any slight grade.

I used my clutch master cylinder and the ZF 6 slave all worked perfect together.

Now I have basically a 5 speed with a granny low, but it also seems to be a lot closer ratio, in 2nd through 6th, it stays in the torque curve better now.

I also used my South Bend fly wheel but had a a clutch and pressure plate built by Tn. Brake and Clutch in Nashville Tn. They put organic lining on one side and a metallic lining on the other, this works great, its smooth and holds my 350 / 750 rwh no problem.

I pulled my enclosed trailer today with my car and all my track plunder and I took off in second just as good as the old ZF5 did in first, I love it.

It seemed several people have asked about this swap, and I always read where people said it wasn't worth it and it was a lot of trouble, but i noticed most that were saying that hadn't actually done one.

I say it's definitely worth it.

 

Did you have to use the transfer case that was originally behind the zf6, or could you use the 4405 that was used in the 97s? I have read that the output shaft is bigger on the zf6, so a transfer case from the superduty is needed. I'm glad that the swap worked out for you.

 

No the original transfer case would not work because of just what you said.


And I got the N/P 273 with the transmission and it's the electric shift version.


I still have to fab the shifter linkage on it or find a N/P 271 the manual version.

 

The ZF 6 is a lot more transmission, I didn't realize how much bigger till I got mine out and they set side by side.


My truck has always been loud in the cab, and I found out there was no insulation under the shift boot.


What was under it originally?

 

A thick white rubbery insulation. You can get a new one on ebay. boot and insulation comes together. It will make a big difference. About $70

 

Thank you brother Barnes I will check on it.

 

How much weight difference would you say there was between the ZF5 and ZF6?

 

Ford F250 F350 7.3 6.0 Diesel 5 6 speed Shifter Boot New OEM Part F81Z 7277 BB

Brand New

 

I didn't weigh the two, but I would say 50 lbs would be a good guess.

 

Thanks, I am going to get one.......

 

What about bell housing and transmission shaft length?

 

It shortened it 13 inches total, that’s transmission and transfer case total. Also sans the carrier bearing, and built a one piece drive shaft.

 

It’s a great swap my brother did the swap to his single cab 5speed 4.10 truck definitely worth it. We actually just used a 4x4 e4od crossmember and drilled 2 new holes for the trans mount. And bolted the crossmember to the factory pre drilled holes in his frame.

 

I got rid of my E4OD and replaced it with a ZF6. As I recall, the E4OD came with a thicker cast aluminum spacer between the engine and bellhousing, the ZF6 uses a thinner spacer. Swapping from a ZF5 to a ZF6 I don't know but I assume (famous last words) that the distance will be the same and no spacer change is needed.

Bob