My '46 261/stock bellhousing/flywheel, AstroVan clutch disc,stock pressure plate-almost 11", running T-5 and foot starter, no probs. I had to have an adapter because of 46 small trans pattern to bellhsng, your 51 has same pattern as T-5 but must make some mods as Lugnutz expained. Lots of tech tips on the T-5s on this site and over on Inliners.org plus others, read them all. Love my T-5.
Best of luck
