What's the year range of zf5 trucks I can use my local pick n pull has atleast 5 zf5's in 1990's f150 and 250s are all the cross members the same and pedle assembly ect.. I have most the stuff drive shafts,t case and mounts and shifter linkages out of my 87 parts truck but no zf5 left and other odds and ends

 

Everything was the same on the trucks till 96, maybe somebody more savvy than myself can confirm. But i am thinking that you could use them.

 

Yeah that's what I was assuming but you never know

 

I went back to your first post, and see you have a 351w. I didn't see what tranny you have, unless it's in a different post.

You can use a zf from a f250/350 that had a 351w or a 300 six. I am thinking they didn't put a 302 in front of the zf in a f250, but if they did that would work also. I have heard rumors they did put a few zf's in a few f150's, but they would be rare and hard to find. F250's and f350's are where you want to look. You will also need to look at 4x4 trucks only, a 2wd tranny won't work.

You will find the zf's in the later trucks. But the clutch pedal assembly won't work from a later truck to a 86-dwn truck, you will need to find the pedal assembly from a 86-dwn truck with a 4 speed and the hydraulic clutch setup, and bolt that in if you have a c6 now.

Get the wires that plug into the transfer case and the tranny, it will make it easier to mate the wiring on your truck. There should be a plug under the brake booster where it will separate from the main harness.

Make sure you get the crossmember and the short upper crossmember pieces. I found the lower flat crossmember was the same c6 to zf, but the zf set back one inch, so the upper crossmembers were different to accommodate the 1 inch difference. My truck already had the proper holes drilled in the lower part of the frame to set the crossmember back, but the zf was an option on my truck, unlike the early trucks, so you may have to drill those holes in your truck.

My truck already had the hole in the firewall for the clutch master cylinder, I just had to unbolt the plate. Some of the early trucks did not have the hole, but had dimples where the holes need to be, so you might have to cut a hole in the firewall for that.

 

I'm not sure what you're expecting or hoping for, but I have a 89 F250 4WD with the ZF 5spd and 3.55 gears, 351W FI. The engine is a bit worn, so efficiency isn't at 100%, but I only get around 10mpg. Maybe a little less or a little more, but within 1mpg any time I've checked...under different driving conditions and with different tires (mpg based on actual distance, not an altered distance from tire size change). I get 17-19mpg in my 85 5.0L FI AOD.
Tune, tune, tune for the best bang for buck.

I've done the math several times when I've considered upgrades or vehicle swaps. It usually doesn't add up if it's solely based on saving money.

I don't think it's been mentioned, but I believe that your engine would be in the age range of the lower compression "emission" engines. There's only so much that can be done with "bolt on" parts...although later year small cc chamber heads technically bolt on.

Re-read your first post...I guess the 351W HO engine would be a higher compression engine.

 

Actually, no. The heads, rods, and pistons were all the same for the 351W and 351HO, so the compression was the same - in the low 8's. The main differences were the 4v carb and the cam, which some say was a marine unit but I have no way to tell.

But you are right that there is only so much that can be done with a low compression engine. Some things just don't get shiny if you polish them. Better heads will bring the compression up as well as the MPG potential. And while an RV cam will bring the power up it won't necessarily bring the mileage up.

You are also right that the payout is a loooong way out on any change such as an OD tranny. But, as Jim or Dave pointed out, there is the intangible of being able to run at highway speed with the engine just purring instead of whining. To me the change from a C6 to a ZF was worth it for that alone.