1981 4speed into a 71 with 3speed?

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Jul 10, 2006
North Pole, AK
Sorry if this is a repost, but I have a line on a cheap, rebuilt 4 speed from a 1981 FJ-40 and was wondering if it would bolt into my 1971 Fj-40 with three-on-a-tree.
I realize that a would need a floor shifter, but do I need a 4 speed bellhousing, support,slave cylinder, or anything else?
Thanks for your help

Hi All:

To use this 1981 vintage H42 four speed transmission will require use of its associated transfer case. Your existing "three speed" t-case has a ten spline input gear; the '81 H42 tranny will have a 19 spline output shaft.

Now, the 1981 "split" t-case is much stronger than the old one piece t-cases from the 1960s & 70s, but to use the t-case parking brake assembly will require some unique parts!

Look for a 1970s vintage H42 transmission. It will have the correct output shaft for your "three speed" t-case and should not be too expensive.

Good luck with your rig!


Not exactly Alan. The '70's vintage 4 speed has a 16 spline output shaft and will require some different linkages that can be had with the '70's vintage tranny.

"Technical Links" at the top of the page should have some ideas of whats required.
Yes, you need a 4sp bellhousing. You also need a 16 spline input gear and a few other extras to use the 3sp transfer case. You could also use the 4sp case. You need 4sp driveshafts too.
Thanks for the input guys. I ended up not getting the tranny,but I did buy a brand-new Downey header and a brand new starter from the guy for $100. Hard to beat that, especially with shipping up to Alaska.


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