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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: chronos on February 28, 2007, 01:27:00 pm

Title: 3/4 ton engine options - repost
Post by: chronos on February 28, 2007, 01:27:00 pm

I am looking at a 1986 3/4 ton. Did these come with a 400 engine? Is there a EASY way to tell a 400 from a 350 engine?? Thanks

Title: Re: 3/4 ton engine options - repost
Post by: VileZambonie on February 28, 2007, 03:39:00 pm

No they were no longer making the 400 in 1986. The best way is to read the casting # on the back of the engine near the bellhousing.

The 400 was used from 1970 -1980 and they only made 4 bolt mains in 71 and 72 if I remember correctly.

Look for the casting #'s

Also take a look at the balancer on the crankshaft. It will not be smooth all the way around you will see it is balanced.

Some say look to see if it has 2 or 3 core plugs on the side but I forget exactly what that reveals. I haven't owned a 400 in about 10 years.

Title: 3/4 ton engine options - repost
Post by: chronos on February 28, 2007, 04:50:00 pm

Thanks , Can I put the rearend from a 3/4 fullsize into a 1/2 ton shortbox?

Title: Re: 3/4 ton engine options - repost
Post by: Blazin on March 01, 2007, 07:53:00 am

3/4 and 1/2 ton axles are the same as far as the bolt in dimensions. The ujoint will require a crossover joint.

Title: different
Post by: VileZambonie on March 01, 2007, 03:35:00 pm

The 3/4 ton will have 8 lug axles and different brakes.

Title: Re: different
Post by: Fast68 on March 15, 2007, 05:10:00 am

the non 1 tons were all 42.5" leafpack spacing

1 ton were 40

1/2 and 3/4 interchange, same width


good luck