1940 Biz Coupe Diff Housing, Ford Replacement

[cardoctor98]

I am building a 1940 Biz Coupe with a 389 Tri-Power.
It will have a Scotts 4-Link, and Ford Diff, with Ride Tech's. Does anybody know the Stock Flange-to-flange dimension for the housing? I want to narrow 3 inches on each side, for a total of 6 inches narrow...
Thanks in advance...

[Larry]

Are you referring to the measurement between the brake backing plate axle flanges?

If so, I can't find anything measurement-wise other than the tread width of 59" (shown as for all models- which I am surprised about considering the big 29 model). I don't know where they measure the tread width from either.

I'm assuming you don't have the old rear end to measure from. I wish I still had mine laying around, but it was sold long ago. If it helps, I slipped a '76 Nova rear end in my '40 model 2519 and it was a perfect width match (perhaps a 1/2" or so difference, I don't remember). Maybe you can find that measurement easier than from an old '40 car.

How do you know you want to narrow it 3" if you don't have the dimensions yet? Don't forget wheel offset and fender well room too.