Early style sb water pumps

Blackhatguy said

... you can't mix and match parts from pre 69 and post 69. The water pump snouts are different lengths between the cast early and aluminum...

Click to expand...

I did, but not advised. Yes, the aluminum pump is ~1" thicker. I had to get creative with pulleys and belts, and no way to fit a clutch-fan. I went that way because a neophyte and bought the only radiator they listed at Autozone (for ~1972) and picked the aluminum pump to match the radiator, plus it was half the cost and I thought less corrosion since bolting an iron pump to an aluminum timing cover to an iron block = "battery". Good that I removed the timing cover to change the camshaft since I found it was almost corroded thru (leaks coolant into crankcase).

Besides cost, the downside of aluminum heads is more risk of warpage and head gasket leaks, but most cars have had that w/ iron blocks for 30 years. The early slant six was a rare reverse - aluminum block with iron head.