You can squabble at length about what fits what .. and if you have enough determination .. you can make many a blade, fit a tractor it was never intended for .. however, at the end of the day, dannygcat still hasn't yet got his cutting edge and hardware numbers .. so here they are ..

Cutting edge P/No's - D4 & D2 .. img171.imageshack.us/img171/4978/cuttingedges1cd3.jpg

End bit P/No's - D4 & D2 .. img117.imageshack.us/img117/5946/cuttingedges2np9.jpg

Nice chart but the bolting count doesn't match what is shown in the parts book for any of the four serial number groupings for the 4A2001-up blade cutting edge nor the 67E1-up with single cutting edge nor the 67E4791-up with three piece cutting edge.

That's interesting - because the chart is from a genuine Caterpillar Parts Reference book, #6, Issue B .. dated 1960. I can only suggest there has been a typo in the chart. What difference in count have you come up with? - and is it a difference in cutting edge or end bit count?

I would imagine that if one were to take Oz's chart to the parts counter, it would be immensly helpful to the parts man, and a solution would be had in short order as opposed to splitting hairs like a lawyer.

The problem appears to be in the parts book bolt count.
I checked my blade and there are 18 bolts in the center and six for end bits.
In the parts Book:
Serial # 4A2001 - 4A2456 shows a correct total count of 24
Serial # 4A2457 - 4A2620 shows a total count of 21?????
Serial # 4A2621 - 4A2921 shows a total count of 21?????
Serial # 4A2922 - up shows a correct count of 24.

Same count for both standard and heavy duty cutting edge.

My mistake on the 67E, count is correct for the cutting edge once you deduct for the end bits.

I would like to thank everyone for responding. I was finally able to reach my tractor. My tractor is located in the "back 40" and it has been very wet in the midwest (Illinois). The serial number tag is missing (of course) but I was able to discern the number after some sanding. The serial number is 2A1575. I was able to look at a parts book (not mine) yesterday and hopefully have the correct parts numbers. Thank you.

A 2Axxxx is normally a narrow gauge blade for the 6U tractor. The 4Axxxx is for wide gauge 7U. I have seen them stamped wrong (I own one) so be sure to check.

What are the dimensions of a 2A vs. 4A straight blade? The blade does fit appropriately on my tractor (D4 7U). I must admit, the 2 (2A1575) is difficult to read but you can see the number. Thanks, Old Magnet.

If it fits the 7U and doesn't show any signs of welded on extensions then it would be the 4Axxxx version at 8 ft. 2-1/2 in. length. The 2Axxxx is 7 ft. 2-1/2 in.

My CAT PSK shows the 2A as a 4S dozer, which uses 1-4T2980 edge (59.9" long) with 15 bolts, 5/8 x 2, and 1 each 9F7073 RH and 9F7074 LH end bits with 6 each 5/8 x 2 1/4 bolts.