I am qorking on installing a Toploader from '70 Torinio 429 CJ in my '57 Bird today. Thought I had measured everything and was in good shape until I discovered that the rear mount on the toploader is about 1" shorter than  the mount on my 3 speed. Trying to figure out exactly what the difference is. Near as I can measure it is 1" shorter. The guy from Toploader Heaven says it is about 1". All I need to make it fit is a spacer between the frame and the rear mount. Have a temporary wooden spacer there now for the purpose of fitting the shift linkage. If it is off slightly it should not be a problem but would like to get it as close to right as  I can. Anybody ever ran into this one and have an exact measurement?