I was curious if anyone can tell me if axles out of a 73-87 3/4 or 1 ton pickup or suburban will bolt up too a 73-87 K5 blazer? I have weak a** 10 bolts that need to come off a.s.a.p and I need to know what axles will bolt directly to the truck without modificatons a dana 44/ 12 bolt combo would be good but I would really like to step up to the dana 60/ 14 bolt combo  

No burbs ever came with D60's in front nor did any 2500 P/U's. 3500 uses same front axle as 1500 except with different hubs for 8 lug wheels. As far is bolt in, 2500 axles are a direct bolt in as is a D60 out of front of a 3500. In rear there can be a slightly different pad spacing on 3500 axle. You will need bigger Ubolts and plates. If you do not lock front axle you can run 36 or so up there and get by with stock axle even if you play a bit hard. If you choose this route you could install a GM 9.5 in rear which is about the equal of a D60 and can be had in 6 lug hubs and weighs about 85 lbs less than 10.5 too. It is a good rear axle and often over looked for 1500 upgrades. The 9.5 has been around since early 70's and is still being used today.  

SnoMan:
No burbs ever came with D60's in front nor did any 2500 P/U's. 3500 uses same front axle as 1500 except with different hubs for 8 lug wheels. As far is bolt in, 2500 axles are a direct bolt in as is a D60 out of front of a 3500. In rear there can be a slightly different pad spacing on 3500 axle. You will need bigger Ubolts and plates. If you do not lock front axle you can run 36 or so up there and get by with stock axle even if you play a bit hard. If you choose this route you could install a GM 9.5 in rear which is about the equal of a D60 and can be had in 6 lug hubs and weighs about 85 lbs less than 10.5 too. It is a good rear axle and often over looked for 1500 upgrades. The 9.5 has been around since early 70's and is still being used today.

"3500 uses same front axle as 1500 except with different hubs for 8 lug wheels."  I think snoman meant the 2500 axles are same a 1500 axles except for the diff hubs with 8 lugs.  in the original post you said you were looking for d44/12 combo well the 12 bolt rear is really no stronger then the 10 bolt you have now, for tires up to 36 inc tall i would leave the front 10 bolt or d44 alone but for the rear go for the 14 bolts either the 9.5 semifloater or the big boy   10.5 full floater axle. Ive got an 8 lug d44 and 10.5 14 bolt combo in my blazer running 35 inc tires the rear is gonnna be detroit locked pretty soon and i am planning on putting a limted slip up front to make it really unstopable  

81'... on the 9.5" sf rear  

Yes it was a typo, I was was thinking 2500 but somehow 3500 came out. I have heard of a few 1 tons making it out of factory with D44's up front too.