Not sure if this is the right section for this but when I was replacing my heater core in my 64 about 5 years ago, we couldn't find an exact replacement.
Looked at everyhing logical (Impala,Bonneville,Tempest,Chevelle) & nothing matched size exactly.
Think I ended up using one just a bit shorter & had to shim it with a stick?
'64 Parisienne CS "barn find" - last on the road in '86 ... Owner Protection Plan booklet, original paint, original near-mint aqua interior, original aqua GM floor mats, original 283, factory posi, and original rust.
