So I've been looking and I can't find what I want to know. Is it possible to get a 5 speed transmission for my 68 Ford F-100 with a 390FE? I currently have the original 3-speed automatic transmission and I'm only gettin 7 miles per gallon. I was hopin to get a 5-speed stick...any help?

 

Not as a straight bolt in...you'll probably have to get an adapter of some sort and plan on doing some modifications to make it all work. A lot of 5-speeds (like the ZF) have integral bell housings and none of those were ever made to fit the FE block.

But 7 MPG out a a 390 in an F-100 is pretty low...unless you have a number of mods done to it and have a lead foot! I'd say you have some other issues you need to address to get you up into the standard 10-14 MPG range that most of us see.

The closest thing to straight bolt-in I can think of (just speculating wildly here) is the Getrag 5-speed offered in the Dodge trucks when they first started offering the Cummins ('89-'93) before they switched to the NV4500 due to reliability problems with the Getrag. The Getrag, for some reason, was built with the standard Ford transmission bolt pattern so it will bolt up to a Ford bellhousing. But the Getrag input shaft is both larger diameter and longer than the Ford, (like the typical NP-435 4-speed) so you'd need a spacer and an appropriate clutch disc, and it's probably still not worth the hassle due to the fact that the Getrag is a POS, though the likelihood that it would hold up better behind an FE than the Cummins is probably pretty good.

This has come up a number of times already and there have been a number of solutions tossed about, but off the top of my head I don't recall what alternatives were offered. Perhaps some others will chime in here...

 

That cracked me the hell up

 

Glad I could help make your day...

 

Ok, I have been lookin at the T5 transmission by Borg Warner, could that be made to work?

 

The clark 5 speed found behind 361 and 391 FT motors in f600 and f700 trucks from the 70's can be made to work.
You will need a custom flywheel. They are a big heavy transmission and the final gear is 1.1 same as the np435. but it has closer gear spacing and a lower 1st. Use with tall gears in the rear and that would work.

 

The T5 has a different bolt pattern than the standard Ford transmission pattern, as well as a longer input shaft so yes, it could be made to work with an adapter/spacer between the bellhousing and transmission.

However, even the World Class T5 would be marginal in its ability to stand up to the torque of even a stock 390. The WC T5 is rated at 300 ft/lbs of torque while a stock 2bbl. 390 puts out around 375, so you can see it's not a good match. The T5 can be upgraded to handle more torque, but it's not cheap. By the time you're done, you might as well have just bought an NV4500 and swapped that in instead.

Check out the Domestic Truck Tranny Guide for tranny identification and ideas of what's available:

Domestic Truck Tranny Guide

 

Speedway motors makes a new steel bellhousing for FE engines to accept a T-10 Four Speed T-45 or Tremec TKO 500 or 600 transmissions.

I believe a TKO 500 will live quite well behind a fe as it is ratted to 500 FT#

They also offer the same type bell for 385 series big blocks.

Garbz

 

Do you have any idea what gear ratio you have in the rear ?
If they are pretty low, like 4.10 to 1, maybe you might want to consider
highway cruising gears like 3.50 to 1, or possibly 3.00 to 1, and keep the transmission you have. Might be more simple.

 

Don't know if your question got answered but An NV 4500 out of an early Chevy pre 96 has a standard 4speed bolt pattern and will bolt up to a standard bellhousing. It also uses a standard 10 spline clutch disc.

 

ZOMBIE THREAD ALERT.

A short-shaft TKO-500 is a bolt on and can also use the mechanical clutch linkage.

 

2X on figuring out why you're at 7 mpg. I have a stroked FE, big carb, and no vacuum advance but get just over 8 mpg city commuting and I'll get just over 6 mpg on the freeway with a 5 ton trailer hitched on the back. High way driving while empty I get over 11 and would expect you to get at least 11 and possibly 13 mpg.

Your timing is off, need a tune up, or air/fuel is way off.

On second thought, you do have an auto so maybe that sucks a little but I still think your mpg is low.

 

I agree, there are a lot of things that need addressed on the mileage issue, which are all much cheaper that a tranny swap. I was looking for a flathead adapter online recently and came across lots of engine adapters for FE, even for a 700R4, which I would do before all the work of a manual conversion.

 

You can also use a Dodge NV4500 and an adapter made by AA. You have to cut about half an inch from the main shaft. And you have to get a unique through out bearing also made by AA. Think that's about it for you can use your stock linkage or you can go ahead and convert to hydraulic.

 

To answer the tranny question, for my situation I'll go with a gear vendor overdrive should I decide to spend the money. You can likely do a NV4500 for less.