I'm looking at getting a work/project truck with the 6.5. What are the major differences in the '95 Thur '00 engines. I've heard that the '99-'00 are the best years for the 6.5. Is that true? Which one, or ones, gets better mileage? Which one is the most reliable? Thanks for your help.

IMO, Stay away from 97-00 with piston oil spray cooling. From an effeciency stand point they are practically identical. 92-96 are good blocks, but I'd recommend the 97+ cooling upgrade and 01-present are excellent blocks high nickle content and piston spray, but they'll cost you and they're hard to find.

Was the '99 the first year for piston spray? What's wrong with the piston spray motors? Are there differences in injection pumps from '95 to '00? Wasn't '01 the last year you could get a 6.5 in a truck(3500HD)?

Hummers as of 2005 still have 6.5's, Express vans had it though 2002. When piston spray was introduced GM drilled the block for oil passages, where these holes are drilled cracks develop esspecially on a modified engine. By 2000 GM had figured this out hence the higher nickle content to strengthen the block against cracking.

So '95, '96 or '00 (I want the '95 thru '00 interier) is the way to go with '97 cooling update? How were the injection pumps on the '95 and '96? Does anybody make a mechanical pump for that year engine? By the way, thanks for the help.

As far as I know all the '95-'05 use 5521 IP's, I could be wrong. I wouldn't worry about the quality of the '95 or '96 IP as it is almost guaranteed that it has been changed, probably a couple of times. I totally agree with you on the interior that's why I have a '95, as far as the cracking block problem I just got lucky cause I didn't know about that problem untill after I bought my truck. I wouldn't look for an '00 as these probably do not have the high nickle block, unless you get a smoking deal and factor in that you will probably need to change the engine some day.

Okay, I'll bite.. there is a difference between a 1994 and later? Mine looks like a 1996... what's the diff?

SQUARE DASH IS THE BIG DIFFERENCE, 95 and up have the more rounded dashs, starting with 97's the half tons came with passenger airbags, and NO your spouse does count as one either, standard i believe. Also the seat lay out and cushions got way better in 1995.

1995 was the major interior overhaul of GM trucks and is also the birth year of the Tahoe name(death of full size Blazer 1994) and 4 door Tahoe's and Yukon's which never recieved the 6.5 TD. Except for tiny details the only major change in this interior 1995+ as mentioned was the passenger side airbag .

Can you get a mechanical pump for a '95 or '96?

Mechanical pumps (begin as DB2) can be put on any engine. Starting in 94 they had DS4 pumps (electronic). Physically, either pump will run on the engine. The fun is getting the computer to forget it's "other half" out there on the pump.

DB2 more reliable. DS4 you can get more power.

If you are going to undertake a "project truck" I wouldn't fear the DS4. There is more than enough experience housed on the site to help you out,

.....and make stealers shake in their boots.

Well I would like it to be as reliable as possible. The railroad doesn't like it when you're late. I don't like to see all the miles going on my dmax so fast. At any given day I could be driving 2.5hrs one way. Work/Project truck so I can work on it and drive it to work and not care about the miles.

How hard is it to switch to the DB2 pump as far as the computer goes? The DB2, is that the pump from the '92 model? '92s were mechanical right?
Anything else on the '95 or '96 to look for as far as problems or issues? Sounds like the '97 cooling update is a must.

yes all you need is a db2 pump, the matching fuel lines and a trannsmission controller

Sounds like the '97 cooling update is a must.

I beg to differ.

I don't have the dual cross-over in my 95, and my coolant temps never get above 210 pulling my 4000lb boat no matter how steep the incline.

Maybe I'm just lucky. Maybe my truck is one in a million. I don't know, but I do know at this time I have no intention of installing the dual crossover.

Just my .02.

I feel like the other hold out, Wade. Plus I've noticed no rise in temps at idle with the a/c on with a new radiator recently installed. Last summer I was hitting 210*F if I idled for a few minutes. This last week it hadn't risen more than 5 degrees in 30 minuites. I guess my cooling efficiency is up.

Anybody else know what to look for on the '95 or '96, or anyother model 6.5? Problems or anything at all?

Only significant difference between '95 and '96 is OBD1 ('95) and OBD2 ('96). If you want to increase the power by way of the ECM '95 will run you about $250 for a new chip and '96 will run you about $600 for a PCM re-flash. It's easier to read and diagnose your own codes with OBD1. This threads making me want to run out and get more '95's.

That's good to know, thanks again. Anything else??