4 bolt main
4 bolt their stronger better lasting
1500--2 bolt, 2500 4 bolt
The difference between a 2 bolt main and 4 bolt main is how many bolts hold the caps that hold on the crankshaft. (A 2 bolt main has 2 bolts to every cap and the 4 bolt main has 4 bolts to every cap) A 2 bolt main should be able to handle 500hp as long as you don't push it above 5500RPMs.
no cause a 4 bolt main has 2 extra bolts on each main
i have a engine with this # and its a 2 bolt main
4
That would be a 4-bolt engine in that truck.
To tell if your engine is a 2 bolt main or a 4 bolt main. Turn the engine upside down on an engine stand. Next, count the number of bolts on each main bearing cap. if there are two, then its a 2 bolt main. And if there are4, then its a 4 bolt main. This applies to the three center caps. The front and rear are always 2 bolt.
I can't answer your question but I can say that my 260 hp 350 Mercruiser has 2 bolt mains and a 4 bolt rear main. Go figure! So I take it from your question that you also have 2 bolt mains with a 4 bolt rear main.
should be 4-bolt
If its a 1/2 ton it will be a 2- bolt main, You can run the engine # if you need to know for sure. But i'd bet its a 2-bolt
If it's the factory engine, then it will be a 2-bolt main engine.