70s style as in poly engine or LA 318 engines?

318s are internal balance 273 318poly LA318/340 interchange balancer.

EXTERNAL balance LA360/B400/RB external balance and cast crank 440 interchange ** 440 bullet nose damper says cast crank 440 ONLY. ( I run a weighted 400 TC with my 440 cast crank only damper)

I got a replacement damper that is internal balance but has a bolt on weight for a 360 and another weight for cast crank 440 only.

IIRC there may be a external 340 crank??

I have a couple good 318 dampers that are early 80s to mid 80s you can have as well if needed. they need a home other than scrap yard.