Trany ID question

[rrhorton]

When I purchased my 31 coupe with a B model engine installed with a Mitchael Overdrive, the seller gave me a transmission he stated was a full syncro that could be installed with an adapter. Can anyone tell me what transmission I have. Top of bell housing has stamped: *18-5144722*
The ones look like a short topped T with no bottom line. The transmission and bell housing are a single casting rather than a 2 piece like the one installed in my car.