If we’re spending someone else’s cash why not just mill your own? I’m sure it could be done under 20k
The thing with the 57 9 inch is as some others said, Width. it fits a lot of cars without a lot of modifications. I've got a 74 F150 nine inch that has the right gears but is going to cost a chunk to narrow. That's the key, Get one that works or spend money to get one to work.
I sell them for 3-400 bucks when I get them, obviously I pay less, usually free to 500 for the parts car
I'd be more suspect of a stock diff than the axles. From personal experience, a 6000 RPM 1-2 shift with my 383 Chrysler obliterated the spider gears in my stock 57 Ford rear. The axles were fine, and I replaced the carrier with a Currie billet trac-loc for the 28 spline axles and never has another problem.
Many people think that 1957 9" housings are the same as 1958-9. The widths are the same but a true 57 housing does not have the dimples for jig location when manufactured. I do have one 1957 complete axle ***embly. I'm keeping that for a Model A roadster build since you can see the entire axle. I'd say a true 1957 axle housing is worth $300. Movin/on
I'd imagine that a similar shift with my 390 FE on pavement would have similar results as you did with your Chrysler, but we were on wet clay.
Fortunately I stocked up on 57 to 59 9 inch and maverick 8 inch in the old days for $50 or less for my personal use but they're all worth $200 to $300 each anymore if they are any good and have useable gears.