GM 1994 GMC Yukon 2-Door SLE 6.5TD Updates

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Keystone Cruisers
Oct 4, 2009
South Central Pennsylvania
I tore things apart to work on updating the interior of my Yukon - recovering the headliner, putting in sound mat, new carpet, and other upgrades.

To start, I found a pair of GMT-800 bucket seats for a good price and made up brackets out of TS2x4x1/8 to mount them. The brackets mount to the original bolt holes in the floor pan with holes in the tops of the brackets to reach the bolts. Then the seat rails bolt to the tops of the brackets. It took several iterations of putting the seats in, marking things, pulling them out, drilling the holes, and so forth to get everything lined up but it all worked out perfectly. I started by placing the console to get those holes in the right place. Then the inner seat rails mount to those same bolts, so that enabled me to locate the holes on the outer rails. Sitting the seats right on the floor pan put them much lower than the original seats (the GMT-800 must have higher corrugations in the floor pan), so the 2" of the tube steel put them at the perfect height.

I like a firmer seat with some side support, so the GMT-800 seats are much better than the original bench (or the GMT-400 buckets).

Seat Brackets Collage 001.png
Seat Brackets Collage 002.png
This week has been spent doing battle with removing the riveted GM half-ton balljoints. I did the top ones first and they weren't too bad - I just had to grind the heads off and then pop the remainder out with an air hammer.

But the bottom ones were a serious pain. Grind the heads off, drill them out (drill, drill, hit with air hammer, drill, drill, sharpen drill bit, drill, drill, etc) far enough that the air hammer was pushing them through instead of just mushrooming them inside the balljoint flange, and then pop them out with the air hammer.

Replacing the balljoints and bushings was a difference of $122 for balljoints and $53 for Energy Suspension bushings ($175) versus $110 for upper and $360 for lower complete arms ($470). For the complete arms, I could get Moog for upper, but lower options were limited (Driveworks?). So, for my work, I saved about $300 and have a better feeling about the components I installed.

Oh, and the local shop wanted $1200 to do the work - again, with questions about the actual components used...

Balljoints Collage.jpg
One of the issues that plagues the 6.5L GM diesels is the battery setup. There is a battery on either side in the front corners of the engine bay, connected across the top of the radiator, ground sides both connected to the engine, and positive sides connected to the alternator on one side and the starter on the other. The OEM cables are undersized and not well made (leading to corrosion), both of which limit function and cause battery drain. Attending to this issue has been on my list for awhile, but I finally got around to ordering up supplies to make it happen.


This one was further butchered by the PO, just making matters worse.

So we're going to take the time to make some good cables for the old girl.
I'm doing up a set of the same seats for my K2500, so I pulled the brackets out to take measurements and duplicate them.

While they were out I cleaned them all up, powdercoated them, and installed 1/2"-13 rivnuts rather than needing nuts to install the seat tracks to the brackets. I used a die grinder to mark each one (PO = Passenger Outside, etc) and the Front of each bracket.

When I did the battery cable upgrade, I still had life in the batteries in the truck so I temporarily terminated the ends to work with the stock side post terminals.

I've never been a fan of the side posts, though. Messing around with the screw-in connections - particularly if you have any additional ring terminals added - is a real hassle and I just don't feel you get the same connection as a top post.

Earlier this year I picked up a pair of Group 34/78 800CCA Dual Terminal Batteries for the Yukon. Until I had a moment to reconfigure the cables, I could continue to use the side posts. Also, once converted, I could still use the side posts for additional connections and also to add in a NOCO on-board battery charger.

The diesel setup with the two batteries has always been hard on them. The alternator charges the driver's side battery, but the starter pulls from the passenger side battery. In a perfect world, that shouldn't be an issue if all the electrons flow as they should. In practice, it always seems to kill the passenger side battery first. The heavier duty battery cables should help and I also make a point to swap the batteries side to side (similar to rotating tires) to get more even wear. Still - particularly if the the Yukon ends up sitting for awhile - the batteries need to be topped off every now and then. I have a battery charger, but it can be a hassle to connect things up and also charging it out in the weather if I can't get it into the garage is another issue. So an onboard charger that I can just plug an extension cord into makes it an easier task.

I had some time to work on things this past weekend, so I set to work...

The NOCO charger is very nicely packaged - if you're into such things.

I've got a TEMCo Hydraulic Cable Lug Crimper that will do from 10ga to 600MCM. It does a very nice job and also comes with plus sized dies for thicker lugs. It even imprints the size into the lug while crimping to confirm that you used the correct size die (the plus sizes don't have this feature). It's overkill for 10ga, but I've done lugs for building wiring as well - service entrances and such.

I'm using Fastronix top post terminals. They're nice without spending a ton of money.

I use a simple marine battery switch to stop the low-level drain that occurs in vehicles that sit often or for extended periods. Just shut everything off when you're not going to be driving for more than a week or two. I have two Optima RedTops that are now over 15 years old afaik. They were never date marked so I can't be certain. One is older than that because I remember buying it back in about 2002 or so! That one is starting to show it's age but it is an original made well before Optima sold off. This won't work if you have electronics that need a constant supply to remember settings, etc.
I've used disconnects, but it still seems that things work better with "topping off" at times.
Bring A Trailer just had a 1994 Chevy 2-Door 6.5TD Blazer go for $35,250. Of course, it only had 4700 miles on it.

Pretty much a twin to my GMC Yukon except for a red interior (mine is grey) and 200K less miles on it.


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