I was told that there are two different crankshaft geometries for ford Lima series engines, one pre 71 and the other for the later engines. Supposably it is possible to mismatch a crankshaft/flexplate with a torque converter. I am currently rebuilding a '79 460 block(d9te-ab) to replace an older one (dive 6015-a2b). Will this cause a mismatch or am I just hearing a bunch of bs?

 

The number is D1VE-6015-a2b which makes it a 1971 item. So yeah you have a mismatch.

 

So I need to buy both flexplate and torque converter for a 79 ford 460 to fix the problem or just a new flexplate?

 

No, the torque converter is neutral balanced in both cases. Only the flex plate is different.

Oh and I though the internal to external balance change was in 1978, but my memory fails me more often as I get older.

 

Wait a minute.. What exactly is your intention? There are several things that pose potential problems. As far as the late block and rotating assemblies. The late block (D9) is built for an external balanced rotating assembly. All components of which are different.An early internal balance assembly has bigger counterweights and will not clear the late model cylinder walls. The flexplates between the two are different and there is a possible converter pilot diameter variance around 68-72 ? You really need to take inventory of what you have before spending a dime.