The T85 and T85N are mostly Ford and Jeep application, the bolt pattern will not be correct. The only GM application for that trans that I know of was in some Pontiac Tempest models, listed as the "Dearborn" transmission, and they used a special bellhousing for that. A much better choice would be to find an SM319 from a '55-'66 car or truck. It will bolt right up to your existing bellhousing, though you may need to swap the side cover for it to work with the stock linkage, depending on what year and vehicle it came from. The SM319 is the same main transmission as the SM318, but with the R10 overdrive. The overdrive unit, except for the adapter, is the same as the one found on the T85N.
