HEI Distributor Cap Quandary

I have a 1103375 HEI distributor out of an 80-85 Chevy 350. Do I need a DR-450 or a DR-450X cap?

What's the difference>

 

Does one cost more than the other?

If so, then one is probably just a premium version with brass versus aluminum terminals, thicker plastic, etc.

DR 450X didn't come up on Rock auto.

 

X is blue

 

The X cap is a blue heavy duty cap, otherwise, no physical difference as far as fitting.

 

X have higher dielectric, copper or brass conductors

 

Blue is pretty.

 

Actually, they're both blue.

Looks like the 450X is the higher quality "Blue Streak" cap. I'll let you know.

The Pertronix cap and rotor I'm sending back are absolute crap. I didn't even think about installing them.