18 spline abody box?

you would need an 18 spline input, after that it's just an a body main shaft and getting the tooth count to work.

but I think it was a 2.65 1st gear on the 18 spline, but can't remember.

I've run mine at the strip and beat the sht out of it o a regular bases even behind the 410cid.
Yeah the 23 will be fine, it's a pretty durable piece.