Pre-68 engines [425, 330] had a different bolt pattern for the flywheel
to crank attachment that the 1968 and up 350/455/etc. engines. So be sure you
get a flexplate or flywheel with your engine.
However, there is NO difference between big and little block flexplates
or flywheels. The bolt patterns are different for early [pre-68] and late
[1968 and up] cranks, but the flexplates' weights' size and location are
exactly the same for all. Rumor has it that Diesels used a thicker metal
for the flexplate, thus making then heavy duty. Wouldn't doubt it. Swap
to your heart's content.
OK, so we all know that these flywheels come in two flavors- early [pre-68]
and late [68-up]. With the bolt pattern attaching it to the crank being
different. The difference is something like the
early one has one hole offset 5 degrees CCW and the later version has that
hole, and another, offset 5 degrees *CW*. Why, you have got to wonder.
So, I was comparing two flexplates [the AT kind] one day, and it looks
to me like the weight is exactly the same chunk o' metal.
From a Toronado standpoint, all flywheels are the same from '68 to '79.
Starting in '79, the
Toronado, Riviera, Eldorado flywheels are a slightly smaller diameter. The rear drive
cars are the same as the '68 and newer cars but are stamped "METRIC" and
have additional converter holes to accommodate the newer style converters
used on TH-200's beginning in 1979. They will work just fine in the
older models.
[ Thanks to Chris Witt, Tony for this information ]