I don't know about a three-speed; but, I happen to have a Dana 4-speed auxilliary, with two under-drives, a direct, and an overdrive.

If I don't go the 9-over route, I intend to put it in my truck.

This combo will give me twenty forward gears and four reverses.

 

we put a 3spd brownie style box in my old mans 90 f350. with the 4.10 gears it makes driving at highway speeds more liveable. don't know the gear ratios but it came out of a mid sixties chevy 2-ton flat bed. dont know yet if it was worth the effort (made all mounts, driveshafts, etc.).

 

Were you able to accomplish this without getting any driveline vibrations??

I am just itching to get this four-speed auxilliary in my Ford.

I don't have the shifter mechanism that goes with it.

I thought possibly one of the four-position Hurst shifters, that were designed to convert a three-on-the-column to a floor-shift, could be made to work for my application.

 

we mounted it about were the hanger bearing would be. kinda like a divorced transfer case. this is a two wheel drive vehicle. dont think i'd attempt on a 4wd. it has a harmonic vibration (not bad, but there) from around 40mph to 50 or so. i think its due to driveshaft angle from the box to the rear axle. old man said he can live with it so we went no further. btw, this is not a job for the timid or non-mechanical. lots of fabbing brackets and mounts.

 

This sounds like most of the things I get in the middle of.

I take it you were able to eliminate the carrier-bearing.

How long is the shaft between the transmission and auxilliary??; a good guess is close enough.

Did you leave the speedometer as is; or did you run a new one to the port on the auxilliary??

My truck is a very long wheelbase, 2WD, F-350.

Thanks.

 

man, sorry no answer for a few days (had to work at work, kinda sucks ) . the carrier bearing is gone, short front shaft, maybe 12-14 inches. old man used a rear shaft from a std cab(still had it shortened). the box is bigger than most would think. left speedo untouched, incorrectness varies according to gear choice . shifter linkage was the biggest pita of all. wanted to bind, couldnt get it to operate consistently. finally rigged a cable set up of a late model car. 3 positions straight line shift