I own a 39 D2 5J and have been told it has a D3 undercarriage. How can you tell the difference?
Vinny

Vinny, I note so far no response. I can't answer you, but if you put a photograph of the undercarriage up perhaps that will stimulate a response.

If it looks like this with spacer bar under the rollers to make up for the difference in diameters than it is a D3 undercarriage conversion.

The track link part numbers and link height (if they aren't worn completely out) will be different. D2/early 933 loader links were 3.00 inches tall when new and 100% worn is 2.75" The later rails ranged from 3.18-3.46" depending on the series of D3/931/933loader. The pitch (link length) is the same on all of them. Usually you can find the part numbers of the links on some of them that you can read still.

When you get to track rollers, then the D3 rollers are smaller diameter and require the spacer that OM shows to bring the rollers down to the correct position. The D2 normally has sort of a rocking horse appearance when you look at it from the side on a trailer or hard ground. The plane across the bottom of the track rollers is a couple inches below the sprockets (and idler if you have the small idlers still).

I don't think you can put a complete D3 undercarriage under a D2. It is fairly common to use D3 rollers and, I'm told, tracks. The sprockets won't fit, but rings could be welded onto D2 spiders.

I have a D2 5J running D3 rollers. It does have the spacer bar under the track frame though not as high as the one in O.M.'s picture. The D3 roller is just a little wide for the D2 chain but it works fine. Conversion was done at Cat dealer Halton Tractor Co. in The Dalles, OR. It has worked great; they knew what they were doing.

Thanks OM. GWH