Hello everyone, long time reader and first time poster .hopefully I’m in the right area for this ? I have a 1955 gmc truck that one trying to get back on the road . My goal is to make it more usable 1 ton ish truck . It has the original 248 engine that I got running . The rear axle is the factory 2 speed and looking at swapping for a more modern dual for a better gear ratio . Doing this will require better brakes, also would be helpful if it was the same lug pattern as the rear . Option 1 convert to 4wd , Not ideal Option 2 try and find another beam style axle that has disc on it or at least can be upgraded easier than the gmc axle Option 3 try and find knuckles that share the same king pin size and swap them . Looking to see if someone has been here and done one of these or something different that makes more sense . Open to other options. The picture is about a year old from when I brought it home .
As already stated......how do you plan to use it ? Weekend duty to haul tree debris to the landfill.....freshen up as is and have fun. Run 2hrs away to an event.......look for a donor RV for ch***is or at least front and rear axle and have fun.
Gm used that bolt pattern a long time. There are hard to find 22.5 wheels out there. There are some later c60s that had the large 10 bolt pattern used on todays semis. Could possibly swap those over if keeping the truck a 1.5 ton. A school bus is an option as well but will have a single speed rear. Newer busses have a wider track width than the older ones. 1tom stuff? A rear swap would be simple. this is a C40. Basically a HD C30. So the frame is similar to C10-c30 trucks. A motorhome rear axle and front K-member was swapped into it fairly easily. 4 wheel disc with Hydroboost. There is a straight axle version of these motorhomes/step vans. These use a smaller version of the gm 10 lug with 19.5 wheels. The 10 lug versions are 4 inches wider in track width over the 8 lug. The 8 lug stuff looks goofy under the larger trucks wider fenders. Places like stovebolt.com (something like that) have a lot of info on brake upgrades and axle swaps.
If ya want it low 8 lug gm P30 suspension graft. Had to use the 8 lug to tuck the wheels to drop it. Flipped a Dana 70 HD on f450 springs and hangers. Hydroboost, stops great. Similar could be done with a ch***is swap from a motorhome/sttepvan.
Basically yes , just use around the house and going to a car show every once in awhile. I will have to look into the rv option thanks
Thanks for the reply, I didn’t know that the 8 lug was that different. Cool looking truck . I have looked at the box truck option but haven’t found exactly what I’m looking for yet . Or people want 8 k for it because everyone is using them for food trucks in my area .
Very cool , thanks for the reply. My family wants me to drop it . I may lower it a bit but still want to be able to use it .
Yes the frame is a common width that’s used even still today on cab and ch***is trucks and larger trucks . Tho for some reason I was thinking it’s 34 ? Either way thanks for the reply
34 inches is the correct outside measurement Common for a long time between makes. The biggest difference is track widths increase on newer trucks. Low and using it? The bus still hauls. It hauls parts often and pulls a trailer. Don’t believe the “can’t use it lowered” myth. I got my box truck parts at the s**** yard. Cheap. I’ve got a motorhome ch***is free for hauling it off.
@sorphan No. It’s static It looks lower in the pic due to how it’s parked. Front bumper is about 5 inches off the ground. Similar clearance for a civic But when using the gm platform, bags are EZ The p30 shares components with c30s But the 10 lug versions have bigger spindles. I have drop c30 spindles in the bus but I also set the suspension clip up 4 inches. Overall around a 16 inch drop A c30(truck) ch***is has a dip under the cab. The P ch***is doesn’t. Its very similar in shape to your gmc ch***is The P series was carried up into the late 90s or early 2000s even though Chevy dropped the C sh***is around 90/91 for 1 tons. Ive seen the newer ch***is used as well. gm ch***is have decent aftermarket support Wheels are where the $$$$$ comes in 19.5 is the largest wheel they made for the 1 ton platform. 8 amd 10 lug. The 8 lug is getting tough to find. Aftermarket has lots of wheels. You can even get semi wheels in 22, 22.5, 24 and 24.5 depending on the tire you want to run. There are adaptors for 8 or 10 lug to semi truck wheels. Even blanks you can drill your own pattern Measure that front track width. Outside tire thread to the other side. I can give you both measurements for the 8 and 10 lug gm one advantage of a motorhome is junk ones can be bought cheap even with 454s
Thanks for the info , as far as engines go I have a lot to choose from . I think keeping the original 248 is cool but I’m afraid I’m going to be disappointed in it . Also if anything happens internally, it’s very hard to find parts and they aren’t cheap. But I have a 89 454 , a 292 , a 6.0 ls , and a 350. Also I can get a 80s c60 for very cheap that has a 366 in it . That truck has Dayton's and a 2 speed axle . So I wouldn’t be gaining anything. I do have a 14 srw that’s in the 90s 454 truck . I could use that and either buy hub adapters to make it dual or try and covert it buy finding the brake parts . I’m finding doing it the right way with brake stuff I’m better off buying a dual axle and sell what I have . Another option is to go to super single, not sure if that would work with axle I already have . I think I should keep my eye open for a junk motor home or box truck . Seems to be the best route .
That c60 would be what I would look at. The 2 speed rear can be awfully nice to have to split shifts with.
That big gmc should have a 270 or 302. Those are saught after. The truck with daytons if they are 20s they can be converted to 22.5 EZ kinda depends on the vision for the truck. Stepvsn/motorhome ch***is swap will drop it The c60 won’t
Thanks for the info , as far as engines go I have a lot to choose from . I think keeping the original 248 is cool but I’m afraid I’m going to be disappointed in it . Also if anything happens internally, it’s very hard to find parts and they aren’t cheap. But I have a 89 454 , a 292 , a 6.0 ls , and a 350. Also I can get a 80s c60 for very cheap that has a 366 in it . That truck has Dayton's and a 2 speed axle . So I wouldn’t be gaining anything. I do have a 14 srw that’s in the 90s 454 truck . I could use that and either buy hub adapters to make it dual or try and covert it buy finding the brake parts . I’m finding doing it the right way with brake stuff I’m better off buying a dual axle and sell what I have . I’m going to keep my eye open for a junk motor home or box truck . Seems to be the best route .
366 is a great engine......in hard working trucks.....but I don't think it would fit your light duty needs without lots of carb.....ignition......cam ? changes
The P30 ch***is seems to get used a lot, if you're on Facebook this group has a ton of great builds https://www.facebook.com/share/kbBe39g4hCVsBdZe/?mibextid=A7sQZp
It has a gmc 248 . The 270/302 little brother . Not all but a lot of parts interchange. From what I have read the 248 is wanted for the people making performance.
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