yes the brackets I recognize look like left alt and right A/c. These brackets on earlier sbc came with short water pump and matching balancer. I unsure if the bracket you have are for short or long water pump. The 69 C10 is kinda of odd with ram horns, by this time the 350 in cars had log manifolds and left hand alts. My advise put as much as can together and check the pulley alignments,
and go from there.
edit I can't recall any 350 w/o the bolt holes in the heads.
GM used the rams horns up until 1972...in '73 they started using the "log" style manifolds..they did use a RH alternator in '69 (and '67-68 too I think),after that they started putting the alternator on the passenger side ,then in '73 they switched to the "long" water pump..trucks used the short water pump up until 1972..
I will need to get a "long style" water pump and the pulleys for one and the crank if I ever put one of the SBC I have in my pickup--both engines were set up for the short water pump,and only had the crank pulley on them when I got them..it can become a nightmare trying to find them individually and have them all "jive" and align properly..|
Sadly the chances of coming across a "matching set" still on an engine at a salvage yard is slim to none around here and they would be unlikely to sell them and "break up" a complete engine..
Aftermarket ones are expensive and usually wont work with any OEM pulleys,your more or less forced to buy the complete setup..
I remember when I had my '69 GTO and I put P/S in it,I stupidly didn't buy all the pulleys & brackets off the donor Grand Prix at the junkyard..
I ended up with an alternator belt that loved to leap off above 3000 rpms because the pulley grooves from the WP to crank pulley were "off" enough to let it come off ,being at an angle..never did find a "correct" pulley for it either..
I ended up running the altenator off only the WP pulley,which led to belt screeching and slipping under hard acceleration..but at least they belts stayed on!..
I cringe when I think of how many "rare" pulley setups I either scrapped or gave away--I had a complete setup off a '69 K10 Suburban that I shouldn't have left on the engine when I sold it,since they were useless for the car it was going into..

...I searched thru the ones I have left and I only have one single groove WP pulley for a short pump,and a few crank pulleys..
True definition of junk:--something you don't need--till you throw it away..
