Rear-end upgrade

[Dusty]

I have decided to put a 9" Ford rear under my '38 Chevy coupe.  I now have a 12 bolt GM from, I think a Malibu.  While looking around,  a Buddy said he had a car that was his Dads.  It is a mid '70s Ford station wagon with a 390 engine.  He is supposed to get the Vin number for me this weekend and also the actual year.  

My question...Is it possible to tell from any of the data plates whether it is a posi unit, the ratio, or what splines the axles are.  It is a freebee, but I will have to pay a wrecker to drag it out of the trees....when it dries up here.  I have a narrowed 3:90 rear-end in my roadster.  I would like to put that gear set in the coupe.  I know that I have 31 spline axles in it.  If the station wagon has 28 spline, can I swap out the spider gears, without having to go through the setup of the ring and pinion again? That way I can put the gear set out of the station wagon in the roadster.

Benny

[GPster]

Being it's a station wagon don't make the assumption that it is the same as a car of that year. My friend that had a junkyard  traded for a "buildable" junk station wagon from another junkyard years ago. The other yard had taken the engine, transmission and rear end out of it for a "stock car" build. My friend was just starting out and he had not gotten any Hollender books yet but he had a few cars from the same year and thought the missing running gear would be no problem. Some Ford station wagons used rear end yokes and universals closer related to 1/2 ton truck pieces. He ended up having a driveshaft built to make all the same year pieces car/station wagon pieces work together. It certainly is not a reason to pass-up on the offer but a trip to identify the pieces might be better than trying to rely on a numbers game. GPster

[enjenjo]

According to the information I can find the 390 engine was only used in full size Fords until the early 71 model year when it was replaced with the 400.

Most wagons did not have a 9" rear, they used an 8.5 rear that was a precursor to the 8.8 used in the 80s.

Most common ratios were 2.50 and 2.75

There is an axle code on the option tag on the door jamb on the drivers door, usually 2 or 3 digits. You can find axle codes on the internet, or in a Hollander manual.

Most had 31 spline axles. If it is a 9", you can change the side gears without resetting the ring and pinion, buy the differential case has to be split to do it. If switching from 28 spline to 31 spline, make sure the axle will fit through the bore in the side of the case, some were not bored large enough for 31 spline axles.

[Dusty]

OK Guys...Thanks for the info...
I'll know more this weekend.

Benny

[kb426]

At some point in time, Ford started using 2 7/8 axle tubes at the bearing end of the housing. In doing a 31 spline conversion, there are some aftermarket bearings that will allow this but the economy of the conversion will change. I've had 2 9" housings that are the 3 1/4" square tube deal shrunk down to the 2 7/8 bearing end.