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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: SuperCab on March 01, 2009, 08:29:20 pm

Title: Suburban 2500 4x4 Questions
Post by: SuperCab on March 01, 2009, 08:29:20 pm

Hi, new guy here.

I'm looking at buying a 1987 GMC Suburban 2500 Sierra Classic.

I have a few questions about it, as I know very little about Chevy/Gmc trucks.

#1 - It seems to have a semi floating 14 bolt rear end. I was not aware of a 14 bolt coming in semi floating, only full floating. Was there a sf 14 bolt?

#2 - What front ends were available on this? It has 10 bolts and manual hubs, although the hubs seem to have been changed from autos. What axle might it be?

#3 - The odometer says 54,xxx miles. I believe it has 254,xxx. What conition would you guess the TH400 trans and 208? tc are in with that milage?

I will probably think of more questions soon. Thanks for any help you can offer.

Oh yeah, it had a TBI 350 engine, but the guy seems to think it was changed to a 400.

Title: Re: Suburban 2500 4x4 Questions
Post by: Blazin on March 01, 2009, 09:08:15 pm

Being an 87 it should have the semi floating 14 bolt rear, and a 10 bolt front axle.

Title: Re: Suburban 2500 4x4 Questions
Post by: SuperCab on March 01, 2009, 09:19:06 pm

So there is a 14 bolt semi floater? and that 10 bolt front is just a GM corprate axle, right?

Thanks for the help.

Also, what gears were available in said axles? what is probably in it???

Title: Re: Suburban 2500 4x4 Questions
Post by: Captkaos on March 01, 2009, 10:28:00 pm

Yes there is a semi-float 14, it started around 1980.
the front is a GM 10bolt.
Gear ratios would be 3.73 or 4.10 for the most common, only way to know for sure it to pull the cover if the RPO sheet is gone.

Title: Re: Suburban 2500 4x4 Questions
Post by: Blazin on March 01, 2009, 10:44:46 pm

3:42's are a common ratio in these as well.

Title: Re: Suburban 2500 4x4 Questions
Post by: Lt.Del on March 01, 2009, 11:03:07 pm

my  1991 3/4 ton 4x4 5.7 sub (http://www.delbridge.net/suburban) has the 3.42's. 

Title: Re: Suburban 2500 4x4 Questions
Post by: levisjohnson on March 01, 2009, 11:30:57 pm

Is that a Mark III interior package (wood).  My mom had one in her 91 extended cab.  She loved it, but I dont care for it too much.

Title: Re: Suburban 2500 4x4 Questions
Post by: hilton850 on March 02, 2009, 02:53:48 am

I agree with axle info others have posted, I have the same axles in my '84 3/4 ton and I haven't had any problems other than self induced trouble.  As far as condition of the transmission and transfer case, it really depends on how well they were maintained and how much they were abused.  I would expect that both have been rebuilt at least once if they really have 254k on them...

Title: Re: Suburban 2500 4x4 Questions
Post by: SuperCab on March 02, 2009, 09:09:02 am

Thanks for all the help guys!

Title: Re: Suburban 2500 4x4 Questions
Post by: SuperCab on March 02, 2009, 11:16:00 am

Another Question:

The TBI... Is it worth keeping the fuel injection or should I put a Rochester or Edelbrock or something on it?

Title: Re: Suburban 2500 4x4 Questions
Post by: Lt.Del on March 02, 2009, 04:08:56 pm

keep the TBI!!    better efficiency, better performance, better mpg...what else do ya want?

Title: Re: Suburban 2500 4x4 Questions
Post by: Captkaos on March 02, 2009, 04:14:40 pm

What he said ^

Title: Re: Suburban 2500 4x4 Questions
Post by: SuperCab on March 02, 2009, 07:33:41 pm

Ok, I guess I'll keep the fuel injection.

Yet another question:

Let's assume it has 154,xxx miles. What condition should the tranny/tc/axles be in then?

Title: Re: Suburban 2500 4x4 Questions
Post by: VileZambonie on March 02, 2009, 07:52:32 pm

You might as well ask a Crystal ball that question. The only way to know is to inspect.

Title: Re: Suburban 2500 4x4 Questions
Post by: SuperCab on March 02, 2009, 09:00:11 pm

What should I look for?