1970 71 72 1973 Chevy 427 454 LS6 4 Bolt Main Block 3999289 Corvette Chevelle.
No stamp on pad. Probably a over the counter 4 bolt main replacement block for a LS6 454. Cleaned and checked for cracks. Bore is .030 over. One head bolt has a heli coil. Front machined for roller bearing bushing.
Part # 3999289 Date G-7-72
Thanks # 135COFF
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