Hi Herm,
I know that the small block has long and short pumps but I don't see it that way for the old big block. My old parts book only lists one number for '65-'70 396, 427 and 454 except the L88. I think that the L88 had a heavy duty ball bearing pump on it. Also checked the pump pulley numbers and the only differences listed are diameters which depend on accessories. No note of long and short on Corvette big blocks.
I also checked with GM Performance Parts and they list 2 big block water pumps. One is a long leg design for use on 454 and 502 crate engines.
This is the other one:
14058915 Aluminum Water Pump
Put your big-block on a diet with this lightweight aluminum water pump. It has a reinforced snout and a large diameter hub with dual-bolt patterns for early and late-model pulleys. This casting has short mounting legs and is used for early design V-belt drive rotation.
Here is what Edelbrock lists in their catalog:
Big-block Chevy - Standard Rotation
Short-Style Pump (5/8" pilot shaft) #8850
Polished #8850 #8860
Fits all 1965-68 big-block Chevy passenger cars, 1966-72 trucks and 1969-70 big-block Corvettes.
Has 3/4" ball/ball bearing. Dimension from block surface to hub: 5-3/4".
Long-Style Pump (5/8" pilot shaft) #8851
Polished #8851 #8861
Fits 1969-87 big-blocks and some 1988-91 heavy duty trucks with Mark IV engines. Does not fit Corvettes or trucks over 1-ton. Includes 3/4" ball/roller bearing. Dimension from block surface to hub: 7-5/16".
Short-Style Pump (3/4" pilot shaft) #8852
Polished #8852 #8862
Fits all 1971-74 big-block Corvettes. Comes with heavy-duty 3/4" ball/roller bearing. Dimension from block surface to hub: 5-3/4".
You'll notice that the listing for the long style big block pump says it does not fit Corvette. That goes along with the GM listing for a short leg pump.
From this I gather that if you buy a pump listed for an early Corvette big block it will be a short leg pump.
Hope this helps,
Tom
