The Stovebolt Site Forums The Shop Area Engine Shop Replacing pumpkin

I need to change to an open driveline but can not seem to find a decent rearend for a decent price. Because of gas prices I would like to get a 3.08 or so ratio. I am going to run a 283 with a TH350. Can the center pumpkin be changed out of my torque tube rearend and what do I look for? Thanks, Wayne

If you'll do a search you'll find that later "pumpkins" will bolt to your housing but you'll have to mount your housing solid. It now is hinged.
You won't find one with a 3.08:1 ratio that will bolt in though.

3.38 will be as high as you can get for the '55-'62 3rd member needed for that conversion.

Longbox55..or someone else: I'm putting a 56 pumpkin in my 52 and eliminate the torque tube so I will be going from a 4:11 rear end to a 3:90 .....what does a 3:08 come out of in 55-62?? A car??

Most likely, it'll be a 3.90, the most common gear in a '56. There was a 3.08 used in cars, starting in '58, but that 3rd member will not swap into the truck housing. There is a considerable differnce in not only the size of the housing and gear, but the shape is different, too (round for truck, flattened oval for car).
I would strongly suggest an overdirve trans with the deeper gear, be it a factory od, T-5, or a 700r4. That would give the best of both worlds, low rear gearing for in town driving, then a higher final gear for highway driving.

ZB3
A good combo you might look at would be a 70s Camaro/Nova. This is a good rear-end for use in an AD truck, the ratios are commonly 2.73-3.73, with higher gears available and they are the correct width for your truck. They have leaf springs, but the perches won't work with your springs. I bought a leaf spring set from Total Cost Involved. It was an easy bolt-in. Good luck.

Late '50s and early '60s GMCs offered a 3.07 but it is a spicer and won't mate to the corporate housing. You'll need to replace the whole rear end and change the mounts, but you'll keep the 6 lug pattern.

Thanks everybody for the responses. I am still looking for a good fit. I have a possible line on a mid 70's 3:43 rear out of an El Camino. I think the width will be right. I already have the 283 and 350 trans. Right now it is only the frame in the garage that I am getting ready to paint and start the assembly of the truck. Next to tackle is the frontend. Have a terrific day, Wayne

Wayne, nice to see someone on this end of the country. How long have you lived in K. Falls? I was there '78 - '82 going to school at OIT. Good luck with your project.

Allan,

I grew up in K Falls and left in '77 and moved back 10 years ago. It is a great place to raise a family. You have a great looking truck. Right now mine is just a pile of parts. Have fun working on the old truck, Wayne

On the subject of rear end gearing, I am also about to tackle a rebuild of the 3rd member. When I look for rebuild kits, they have different sizes, ranging from 7.5 to 9.0, for the GM 10 bolt rear end. If I have a '58 3.90 from a truck, how do I figure out the last number? Is it the height of the ring gear?

The rebuild kits are usually listed by ring gear diameter. The old drop out 3rd member Chevy truck axle (1/2 ton) is a 9.375". One place I can suggest for parts, if you can't find them from the flaps or online, is Patricks. They do carry complete (w/bearings) and lite (no bearings, just gaskets and seals) kits. They also have the spanner wrenches and dial indicator sets for setting the pinion depth and backlash.

Very interesting thread. I will be changing my tranny, drive shaft and rear end. My truck had a 4 on the floor and I plan to install a 3 speed manual with overdrive and I already have a rear end with the 3.07 gears out of my 69 chevelle. I probably need a different rear end. I have a lot of learning to do before all this takes place.

So, can you fit any sized gear smaller than the 9.375" in the same housing? Or do you have to match the housing with the gear size?

No, the housings are designed around the specific ring gear being run in them, they don't interchange.