Which Heater Core ?

Buy both, return the one you don't need.

Doc

Buy the cheapest, I bet they both fit :-)

GMC Gremlin

He didn't mention if it was a 1/2, 3/4 or one ton. Pretty sure the HD heaters were only on the 3/4 and 1 ton crew cabs. But, the HD heater core is a bit bigger and IIRC the HVAC system of a SD truck would have enough room to fit it.

Doc

LONG ago, buy my father purchasing his 1976 K10 step side, brand new, was given the option of a regular and heavy duty heater. He went with regular, but apparently you can have both... at least in 1976.

GMC Gremlin

Hi

It is a 1/2 ton.

Hi

I tis a 1/2 ton.

Im not sure what you mean by :

IIRC HVAC SD truck

but it sounds like you are saying the heavy duty would probably fit ?

thanks

Inline................

No it probably won't. Buy both, return the one you don't need.

Doc

If I Recal Correctly

Heating Venting Air Conditioning (or something close to that)

Super Duty maybe? Chevy calls them HD for Heavy Duty, IIRC.....

GMC Gremlin