Technical 1948 Chevy Fleetline Rear End Swap

I have a 1948 Chevy Fleetline Aerosedan, that is all original. I read somewhere about a rear end swap, where you use the rear end out of a 1963-69 Chevy pickup. That way you can keep the 6 lug wheels but get a 12 bolt rear. I'm looking into it but can't find where I read about it before. From what I have researched online, the 1948 rear is about 60" wheel mounting surface-to-wheel mounting surface and the 63-69 Chevy truck rear is 60.5". I haven't been able to measure mine yet. My car is still in storage and we just had snow last week. I found a 1965-1966 rear and it looks to be more like 62". Has anyone done this swap or did I get things all wrong? Does anyone have a better suggestion to keep the original 6 lug wheels? Thanks in advance for any assistance.

 

Don't know about the 60s rear ends, but you can swap the torque tube with gears from a 50-54 Powerglide car into your existing rear axle and get 3.55 ratio.
That's what I did.

 

Why do you want to change the rear end? If you just want better gears, use a PG car from the early 50s. I had a 48 Aerosedan coupe for several years. I went the 57 Chevy rear end and front disc brake route, so I could run 5 lug wheels (and have disc brakes). Since you asked for a better suggestion than the truck rear end, this is mine. It was an easy driveway swap, took one day. But I also had a th350 and a 250 6 cyl., so I added an open driveshaft. I don't know how easy it is to retrofit an enclosed driveshaft onto a later model open driveshaft rear end. Another suggestion is use the 3 speed and rear end from a 235 open driveshaft car that will work with your bell housing and convert the 48 to o an open drive shaft. If you want to up grade the car a little more, go with a later, full oil pressure 235-it will fit easy. Maybe this isn't a good answer, but I dont know how many changes you are willing to make to the car, and one change often requires a couple of more.

 

Looks like Road Runner has it covered.

 

If you go to a later rear with an open drive shaft you are going to change the trans too unless someone here knows how to put a seal on the old trans. As I remember that trans has a different bolt pattern to the bell housing than anything later so the bell would need to go to. Then there is the mounting problem since we're a lot of changes to Chevrolet drive trains after 54. The 54 PG gears maybe your best way if you just want higher gearing.