I am in the process of converting my 66 el camino to front disc I am using the tall spindle from a late 70's Camaro. Can anyone tell me if there is a dual piston caliper from another GM vehicle that will fit on the factory spindle?

nope

Can anyone tell me if there is a dual piston caliper from another GM vehicle that will fit on the factory spindle?

No, as Derrick said. However, there are some aftermarket versions. Though the concensus is they are actually less effective than the OE units.
http://www.ssbrakes.com/commerce/brakefinder/?make=Chevrolet&model=Camaro&engine=All&year=1977&cat=Front%20Brakes&sub=Quick%20Change%20Caliper%20kits

above link searched as '77 Camaro.

I think the aftermarket dual piston calipers for stock size rotors have less overall piston area than the stock single piston calipers. I have never seen them in person, but I have seen the pics.:D

Well....I guest I am on a mission. I will post my results. Although any assistance would be helpful.

No, as Derrick said. However, there are some aftermarket versions. Though the concensus is they are actually less effective than the OE units.
http://www.ssbrakes.com/commerce/brakefinder/?make=Chevrolet&model=Camaro&engine=All&year=1977&cat=Front%20Brakes&sub=Quick%20Change%20Caliper%20kits

above link searched as '77 Camaro.

Wait, they want $500 for them and then another $125 if you want them colored? For a pair of CALIPERS? If they can actually sell some of those I'm apparently in the wrong business. Heck, they want $200+ for a pair of STOCK calipers that have been powder coated! I guess I saved A LOT by going to O'Reilly's and buying stock rebuilt calipers and a can of high temp spray paint.

Wait, they want $500 for them and then another $125 if you want them colored? For a pair of CALIPERS? If they can actually sell some of those I'm apparently in the wrong business. Heck, they want $200+ for a pair of STOCK calipers that have been powder coated! I guess I saved A LOT by going to O'Reilly's and buying stock rebuilt calipers and a can of high temp spray paint.


Here's where I reference the four thousand dollar strut grille thread and we just shake our heads in disbelief.
http://www.chevelles.com/forums/showthread.php?t=308739

Maybe this stuff is like the field of dreams quote, "If you build it, they will come."

As mentioned, don't think there is any "drop in" factory dual-piston caliper that will play and many of the "aftermarket" dual-piston jobs have less piston area than the stock 2+15/16" single piston job. Wilwood has a "new" D52 caliper that has twin 2" pistons and still uses "OEM" type pads. If you can live without dust seals (and deal with the price) I'd consider them:
http://www.summitracing.com/parts/WIL-120-10937-RD/

Otherwise, you're looking at some sort of brackets, etc. to adapt something.

If you're moving to a 2nd gen F-body spindle and looking for more brake performance, look into the "1LE" 12" rotor setup. There are various articles out there on this -- I think they use the "big car" spindles with the 1LE rotors to get 12" brakes.

As mentioned, don't think there is any "drop in" factory dual-piston caliper that will play and many of the "aftermarket" dual-piston jobs have less piston area than the stock 2+15/16" single piston job. Wilwood has a "new" D52 caliper that has twin 2" pistons and still uses "OEM" type pads. If you can live without dust seals (and deal with the price) I'd consider them:
http://www.summitracing.com/parts/WIL-120-10937-RD/

Otherwise, you're looking at some sort of brackets, etc. to adapt something.

If you're moving to a 2nd gen F-body spindle and looking for more brake performance, look into the "1LE" 12" rotor setup. There are various articles out there on this -- I think they use the "big car" spindles with the 1LE rotors to get 12" brakes.

That's a price I could at least consider, unlike the SSBC ones.

The 12" rotor 1LE swap is what I am doing. Hoping to find OE dual piston calipers to fit even with some modifications. Has anyone tried this?