Hi guys i have on my backyard a Chevy 51 Rearend and today my curiosity made me take off the cover ..i raise it and made the wheel spin and in the gear came with 37/9 theet...which gives u a 4.11 Ratio and thats a fast ratio ,..the question is can i swap the inner components into my 7.5 housing ? or its a 8.2 a 51 chevy rear end ? how can i tell it is a 7.5 not by lookin at it ..i wanna check with a ruler Thanks

The 7.5" like we have in our 3rd gen F-bodies was a new series when it came out in the mid-70's. Nothing from the '51 rear will fit it.

Sorry.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4, 2300 stall TC. Ported World 305 heads, Crane PowerMax 2050 cam. ZZ4 intake, oil pump, pan & baffle. Accel HEI SuperCoil & module. Hooker 2055 headers, 3" Catco cat & 3" catback w/dual-opposite Flowmaster 80. 2.93 limited slip. Spohn SFCs waiting to be installed. AMSOIL syn lubes bumper-to-bumper. Daily year-round driver. Best ET, speed TBD...
57 Bel Air, my 1st car. '66 396, 9.7:1 forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 700 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).