I have a 71 LS5 is it a 2 or a 4 bolt main? Thanx.
2 or 4 bolt main.
Team Owner
Joined: Sep 2006
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From: Westminster Maryland
Hi CVO,
I don't know if there's a consensus.
From what I read it seems like the majority have 2 bolt main bearings but certainly some have 4 bolt main bearings.
I think it's one of those things that for most people matters more in their brain than in their engine.
Regards,
Alan
I don't know if there's a consensus.
From what I read it seems like the majority have 2 bolt main bearings but certainly some have 4 bolt main bearings.
I think it's one of those things that for most people matters more in their brain than in their engine.
Regards,
Alan
Le Mans Master
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From: hot 'lanta suburbs Georgia
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Racer
Joined: Aug 2014
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So, is the "larger threaded fitting" right above the oil filter the 100% telling sign weather you have a 4 or a 2 bolt!!?? If this is the case, then telling them apart is supper easy. 
Is this always the case though? (Bigger fitting on the 4's that is.)
Is this always the case though? (Bigger fitting on the 4's that is.)
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Drifting
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From: Garland Texas
289 block sometimes
445 and 959 block no
Race Director
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From: Millington Illinois
St. Jude Donor '08-'09
I have seen a numbers matching 4 bolt main L48. The line had to keep moving and the workers were not all veterans. If the wrong block went on the line or if supply was low hard to tell what went in or why.
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Racer
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Safety Car
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From: BC
Block is T1020LM on the stamp pad.
Drifting
Joined: Aug 2004
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From: Lubbock TX
Those are the last 3 digits of the block casting number. It's on the ledge at the back of the block on the driver's side, just in front of where the tranny and block meet.