questions about D3B I am looking at

I went to look at a D3B Z its in decent shape but I have some questions. Is there any differences in the "Z" model other than the longer track frame? The guy says its a 88 but I think its a 87 didnt get the serial# but it was a 27Y prefix. Undercarraige is 90% or better but he said it sat for about a year and a few of the pins/bushings are froze up. Is this a problem or will they loosen up after a good long day of running it? Also I noticed when shifting between the gears there was a slight hesition. The outside temp was 28deg when we started it and it only ran for 10 or 15 minutes. Could the hesition be from being too cold or is this a problem. The machine started right up in the cold no either no smoke, straight sheet metal, 4600hrs, tight blade, new seat, all lights, guages work, no leaks, and was painted 6 months ago. Owner wants 12900 obo. What do you guys think? jbeam

Here's some info but watch out.....they seem to have plenty of errors in some of the specifications, a least on the old stuff.

D3's seem to be pretty popular and that price seems in line. Be sure to check it out closely.

Personally I don't think much of the 3204 engine with only two ring pistons, no cylinder sleeves and only two camshaft bearings but there are a lot of them out there.

http://www.ritchiewiki.com/wiki/index.php/Caterpillar_D3B_Crawler_Tractor

I have a 1987 27y- about 4500 hours. bought it last year for $8750---the grousers were worn down and the tracks were about 50%. has 16 inch pads and works well in mud and bog. doesn't like to start under 30 degrees. engine runs great, uses no oil, but have had problems with fuel delivery---screen at transfer pump plugs up (dirty fuel tank??) check tranny filter and screen for debris for hesitaion---there are ports on the tranny to check pressures for all speeds.