The Stovebolt Site Forums The Shop Area The HiPo Shop Rear end advice for a 48 swap

Hello everyone! I just purchased a 1948 Chevy 1/2 ton pickup and I want to change out the 216 to a pressurized 235. The truck is for my wife so I'm adding a 700 R4 auto trans. No towing, just cruising and some highway use. My question is which rear end should I use? I'd like to just bolt it in, and keep the original 6 bolt pattern for the wheels. I've read that the 55-57 Chevy truck rear end is a bolt in affair, and removes the tube driveshaft. Is this correct?

55-62 chevy 1/2 ton center is a bolt in. Other modifications are necessary to the axle for this to work, which include removing the old pivot mounts, and welding new spring perches.

I don't see any problems with the engine swap, but teach your wife to drive a stick. If you need more speed (OD transmission) you will need better brakes.

Thanks! I'm planning on keeping the drum rear brakes, but upgrading the fronts to disc.

That's enough.

48 has huck rear brakes... might as well swap out the backing plates and use the later bendix brakes... it's all found on the same source axle. It is much easier to find parts for the bendix brakes, and they stop a lot better than the hucks.

You may want to consider a 230 or 250 six because the 700R4 is a straight bolt up to them. The 235 will require an adaptor kit which is a bit pricey. With the overdrive (700R4) trans the rear gear can be either the 4.11 or 3.90 since the final in OD is 2.88 for the 4.11 and 2.73 for the 3.90. Go much shallower in rear gearing and the six doesn't want to pull any kind of load, climb hills, or even buck a strong head wind very well. If you are never going to haul or pull anything you may want to use a non-overdrive 350 trans with a 2.73 rear rear. With the torque mutiplication of the automatic they pull that gear just fine and you get the benefit of reduced engine revs in every gear rather than just when in OD.

Thank you! I will do that.

How hard will it be to put in the 230 or 250 six? Can someone point me to some information on this swap?

With that 700R4 ya might just wanna keep the original rearend in it,seeing as how the700R4 is an overdrive trans.In my 55 2nd series I am running a built 350 hooked up to a 700R4 tranny,and stock 3:90 rearend.Good performance and 20 MPG all day long.

His stock rear is a torque tube, there is no way i'm aware of matching a later model trans to a closed drive.

He needs a center section from a 55-59' half ton to get the open drive line. I am doing that very same thing this summer.

How hard will it be to put in the 230 or 250 six? Can someone point me to some information on this swap? check my website i started using 250 and 292 no adapter needed for the trans

Check with Chassis Engineering, they have conversion kits for many engine/vehicle combinations and often have them with a choice of weld in or bolt in. Good on tech tips and advice also.

Thank you!