Have a 1970 LS 5. I think engine is correct but not original.
Anyone out there help me with engine ID #'s
1st pad # is T0521TRH. second # on pad has been either left off or decked.Bellhousing flange # is 3999289. Any info would be greatly appreciated. Thanks.

Here is some different information I located:

3999289....454.......71-79...2 or 4 bolt, some "CE" replacement blocks had four bolt main caps

3999289 1972-78 454-- 215, 235, 240, 270, 2 bolt, car & truck

3999289 454 1972-1979 Two-bolt

STamp info:

TRH 1973 454 240 Truck LS-4 VIN Z, L, 10, 20
TRH 1974 454 245 Truck LS-4 VIN Z, L, 10, 20
TRH 1978 454 250 Truck LF-8 VIN S, 30, fwd
TRH 1980 454 225 Truck LE-8 VIN W, 30, fwd

Have a 1970 LS 5. I think engine is correct but not original.
Anyone out there help me with engine ID #'s
1st pad # is T0521TRH. second # on pad has been either left off or decked.Bellhousing flange # is 3999289. Any info would be greatly appreciated. Thanks.

Did you find any more info on your 454? I'm trying to track down info on my 454 and came across your thread. Mine has the 3999289 cast number, date code is T0529TRH and there is no VIN number on the pad.

Thanks,