<The MGA has a frame while the MGB is unibody. So it is very difficult to fit
an MGB overdrive in an MGA.>
Hmmmmm, I don't think it has much to do with the differences in frame vs.
unibody. The swap could be described as difficult, but with enough
I went crazy during the restoration of my 1956 MGA and installed a 1979 MGB
gearbox with overdrive. Yes, there are numerous considerations, including
modifying (enlarging) the metal gearbox cover and fabricating a new rear mount.
There's some engine-to-gearbox modification necessary, too. Taken as part of
the complete restoration, the gearbox conversion was just another tedious task,
but the results are definately worth it! With the stock axle ratio of 4.3:1
the car does 75 mph at 3500 rpm. Add the convenience of all-syncos, smooth
diaphragm clutch and the robustness of
the later gearbox and the MGA is transformed into a great road car. I have
nearly 18,000 miles on the car since its completion in 1990 and there's another
1,000 miles of trips and events remaining this year.
Color me a very enthusiastic supporter of overdrive gearboxes (there's one
in my TR4A, too).
More specifics are available to the curious.... off the net would be apropos.