Classic/Antique Car Repair: Triumph transmissions, bolt pattern, clutch release

Question
Howard,
This is a reverse engineering question but do you know if I can retrofit a TR6 transmission into my TR3A without modification?
Happy New Year,
Newt

Answer
Hi Newt,
I have never tried to do that switch but there are some differences that need to be looked into to. For example, the sleeve that the clutch release bearing rides on may be different so as to interfere with the pressure plate and the length of the input shaft may be a different length especially the configuration of the shaft where it goes into the pilot bearing in the flywheel. The output flange is different but may have the same bolt pattern but you need to look closely at any recess to see that both are the same size as you should not depend on the bolts for alignment. That is the best I can say. As for you exact question, "Will it bolt up without any modifications?", I don't think so, but careful measuring at the criticle points may make it possible with some modifications.
I hope this helps.
HMF