[60man]

Originally Posted by MOJO Catalina

The Blue one is the 535552 and the unpainted one is the 536194... I've noticed over the years that the "stock" 536194 seems to be less available than the Super Duty one, meaning I've seen fewer of them offered for sale here and on Fee-bay..

Any difference other than casting numbers?

I don't think a heater pipe nipple is tapped in the so called SD one..Pontiac relocated the hose to the passenger side head because of a "gurgle" noise..
The 510 aluminum is cast with the 61 water by pass...

[Jack Gifford]

Troy- You're right, the 540510 has a provision for the pump-interface. But it also has the 1/2" NPT tapped hole for heater-hose/guage-sender.

As for the 535552 being "SD", I'm skeptical. But you need to understand that the whole subject of "Super Duty" nomenclature prior to 1962 is a pet peeve of mine.

[60man]

Originally Posted by pontiac jack

Troy- You're right, the 540510 has a provision for the pump-interface. But it also has the 1/2" NPT tapped hole for heater-hose/guage-sender.

As for the 535552 being "SD", I'm skeptical. But you need to understand that the whole subject of "Super Duty" nomenclature prior to 1962 is a pet peeve of mine.

Yep...aluminum 510 had heater nipple tapped....but the "so called" SD iron one did not..IIR..only difference I could find.
SD not around in 60 is a pet peeve of mine Jack ..
I firmly believe 60 was birth year for SD....maybe not for production runs..but for NASCAR & drag racing..I seem to remember that NHRA made the 510 intake legal for 60...but not legal for 61 model year..??
Next time I see Arnie I hope to ask him his opinion.......