OK - The engine in my 93 blew up and the truck is not worth repairing.
I spent the weekend on line and driving all over.
located three trucks. All are Chevy ext. cab, diesel.
one is an 06 2500 with long box, black, 99,000 miles for $24600.
one is an 07 3500, silver long box, 53700 miles for $29000.
one is an 08 2500, ruby red ( favorite color ) short box, 84500 miles for $29900
What for reasons of less repairs and known troubles and personal choice would YOU buy.

Steve

Buy the 06. It is the first year for the higher power output, has updated injectors, and lacks the DPF emissions equipment. I know of a few 06s around here with 350k without a hiccup.

The 06 will be a LLY or possibly the LBZ, the 07 will be a LBZ or if newer than 07.5 it will be the LMM, the 08 will be the LMM engine. Doesn't really matter as all three of those combinations are reasonably trouble free(meaning they don't have the injector issues the earlier LB7 engines had). Naturally, the life it has lived up until now plays a big part in how the truck will perform and last. If it was me, I would spring for the 08 truck as the "newer" body style has grown on me. Good luck and if you have any questions feel free to ask, I have rebuilt several of each truck you mentioned.

personally I would buy the newest with the least amount of miles. If its only those three then I would go with the 07 or 08. I would keep looking though and maybe expand into other brands. In 2010 I bought a 08 F250 Fx4 with 14k on it for 30 grand. So I think there might be better deals to be had. Where do you live in Alto, my parents live on 92nd st

Short box would be crossed off the list immediately for me. Those are for hauling azaleas, not men stuff

I have the 06 LBZ and absolutely love the power and efficiency. If you avoid the emission equipped chassis your mileage will be slightly better as you won't be burning your fuel up in the exhaust after treatment instead of the engine.
The new body style also has the new seat design which is better for long drives. I hate my old style seat but am going to have it redone like the new style.
Stick with the bowtie. LOL

I had a 05 duramax for 5 years..great truck....recently sold it and bought a 08 exact truck...the ride/smoothness of the 08 is unreal !!! huge difference over the 05...have EGR,DPF/cat delete and EFI live tune...great power and much better mileage again over 05...

We have a really cool 06 Ford. Best tow vehicle I've had. Ck our website for photos

Agree you really cant go wrong in general.
With all of GM mid year model changes, specific engine and body style will be the differentiating points for me.
Need more info.

Take into consideration and check closely if any have had programmers on them. Even moderate tunes can have an effect on transmission life.
How do I know? - I have a "moderate" efi live tow tune of 50-60hp and hurt the trans after 5yr and 60k of not hard use.
Also consider if any have been "leveled". Leveling puts extra strain on ball joints and other front end components, especially if not done "correctly" with a full Upper control arm kit like Cognito.

As above -
long box only for me.
I don't know if GM changed the rear seats on Ext cabs but CC is a big change between lay down giving horizontal space vs fold up giving more vertical.

Hitches are very weak on anything before 2011 so plan on upgrading, Curt is a good choice.

the 06/07 duramax is a good choice, mine has 178k miles of hard use so far. Must keep all the filters clean. Not sure if I will ever own a better vehicle. But am going to buy a 2014/5 Denali Duramax as soon as I can order one