Okay 85 f150 300i6 currently a t-18 8.8 with 3.08 gears. Im wanting a 5 speed, sounds like the t5 is cheap plentiful and has good gears. If I understand correctly I'd need a s10 tranny for gears and shifter location but a small block ford bell housing. And swap the input shaft for a 10 spline 11' one. My t18 already has a hydraulic clutch. What I don't know is driveshaft length and what to do for a crossmember. Anybody ever done this? Will the shifter clear my bench seat? Will the t5 withstand a mild 300 build? What about the speedometer? Thanks as always guys!

 

First, if you are going to tow or haul heavy stuff, I don't think the T5 will last. It is nowhere near as strong as that T18.

Some info in these. I was going to do this in my '85 but it never happened. You need an adapter due to input shaft length.

The Ultimate T-5 Swap Article

T5 Swap, T5 Conversion, Mustang T5 Swap, Auto to Manual Transmission - FordMuscle

Adapter here:

Inline-6 Transmission options using a TREMEC T5

I had a link showing a guy doing the conversion, but it is not available or is gone.....

The Cobra Mustang trans has the highest torque rating, and a decently low first gear. The T5 parts interchange easily, thus the Chev S10 tailshaft housing can be swapped on there for a different shifter location.

You will have to fiddle with the cross member, but nothing major iirc.

DS is a question mark--don't know.

See if those links lead you closer to more gears.

 

Find a ZF5-342 with the small block pattern. It came behind the 300 and 351 in F250-350. It should be a bolt in. For light duty the Mazda 5 speed that came in the F150 with the 4.9 will work and be the cheapest option of all. Again, both should be close to bolt in installs.