I narrow my own 9 inch rear ends ,still cost around $75 for a wrecking yard housing to narrow ,depending on how narrow you go you can reuse your axels from your 8 inch . There were two axles used in the 8 inch though ,same spline but smaller shaft in the middle ,you want the thicker axles. 8 inch and 9 inch share the same axels ,unless it is the big block 31 spline