I'm wanting to convert my 97 3500 from automatic to 6 speed. Has anyone done this? If so what is the best tranny to use and what all will i need to do it? And did you run into problems along the way? Thanks.

 

My early-98 (97 with the updated cab) got treated to a G-56 about a year and a half ago. It was a shop-job, since I didn't have time, tools or talent to really do it myself. We needed:

Flywheel and clutch. I went with a 13" Southbend setup that's rated to hold 900 or 1000 lbft. My output's about 7-800 lbft, so that's enough clutch for me.

A pedal set---came from the tranny's donor truck--- Clutch hydraulics were in the box from South Bend

An adapter/clutch housing. I think that came from the donor as well.

Seems like Mike only had to move the tranny-mounts from one pre-drilled/pre-designed location to another ---WOOHOO! NO FRAME MODIFICATION....as far as I can remember

The place where it got interesting (read an Oh, My God! moment) was for the output to the transfer case... there was yoke-changing to be done. I don't remember the specifics, but, I do remember that my T-case was about shot anyway, so we hybridized the front and back halves of the shell, and (luckily, the donor truck, a rollover victim, was a 4x4, as well) and then the mating-up worked good.

There was an overall-length issue, so the drive shaft, and the front propeller shaft had to be shortened and lengthened.


At the end of it all, I'm happy as a damn clam! But, in all honesty, you might really be better off getting a manual-built truck. I did it that way, myself, because "Tiny" hauls around more of my family's memories than a common work truck normally would.

 

That is a bit much haha. Well i don't think i'd have as much of a hard time since mine is 2wd. Thank you for the input it helps a lot. Finding a donor is gonna be a chore i believe. What was your overall parts cost? I'd do the labor myself

 

Dude, I don't even friggin' remember. I do know that by the time it was all done, I think I'd pretty-well funded Mike's purchase of some really nifty shop equipment. He had the transmission up in the attic of his shop. The trans might have been $2500-ish, and I don't even know if I got a steal, or if I got ripped off. The clutch/flywheel were list-price from South Bend's website, and Mike told me I could have saved some $ if he'd ordered it, because he'd have gotten his company discount. Dunno. Seems like the whole enchilada was about $12-15K, but, I've had some seriously stressful times in the last 30 months, and it's all somewhat of a blur, with dollar-counting being near the bottom of the priority pile.

 

Could you elaborate on the transfer case modifications please, Geddy'sUncle? I have a 97 with a fried auto and an NP241DLD. I already own a G56 and new clutch but the output doesn't fit the 241. I would love to find a DHD or a 271, but I'm not sure what works or what is involved in any modifications.
thanks for any help.

 

As near as my addled brain can recall (keep in mind that being me would kill somebody normal), my OEM tranny's output shaft was smaller than the G-56's, as was the output shaft at the rear of my old t-case. The donor trucks shafts were larger, both in and out. Simplest solution would have been transplant'em together, and then just get a bigger U-joint for the drive-shaft. There was some reason why that wasn't feasible, and I don't remember what it was.

The solution that we utilized was something fortunate. Turns out that both trucks used some kind of NP-241 variant, so, the front and rear casings would mate up perfectly. So, we used the front-half of the donor's case, freshly inspected/replaced internals, and my old back half. VOILA! shaft compatibility both into and out of the t-case! As mentioned a few posts up, there was a length difference, so the lengths of the drive-shafts both needed to be adjusted.


It was an adventure, but, I've now got a granny-gear/4-lo crawl of about 0.5mph at idle, and maybe 3mph at 1/2-throttle. I've got positive contact from the crankshaft to the tires all the time, and, because the automatic is gone, there's not nearly as many places for leakage, and no heat transfer to the radiator water. 6th is not as fast as the old OD's ratio, so I gave up a bit of top end, but, perhaps I shouldn't have been screaming down the highway @ 105mph anyway, in something that weighs 8000lb.