Chevy K20 Rear Axle

Having problems trying to find a locker for it. Two questions; what is it, how to change it.
How to tell between a h052 and a h072? Sold to me as a 3/4 ton
truck, but armchair mechanics have told me it might be a 1-ton. The VIN is for a 3/4 but the arguments are pretty strong. Seems to be it has had some modifications to it. Lot's of trouble determining brake drums, then more trouble finding a universal for the drive shaft. The Tractech folks told me it is a h072 after seeing these pictures.
Whatever it is I will probably, not sure yet, swap it with a Dana 60. Never did this before and would like to avoid surprises. Where/what is a good source of instructions for swapping a rear axle. Maybe I should replace the springs while I am at it? Help me avoid surprises or having a project that takes forever.
Pictures at: http://www.geocities.com/magooasdf
FRONT DIFF It has two sets of numbers on the case front view, drivers side top C-31256 front view, drivers side bottom 44-5F
REAR DIFF It has one set of numbers on the case front view drivers side 3934635 but it is not clear, it may be S931635 It might be an Eaton h072 1-ton It should be an Eaton h052 3/4-ton
1971 Chevrolet K20 Fleetside long bed 3/4 ton pickup 4WD 350 4-speed manual transmission with granny gear Manual hubs
All ideas appreciated.
Thanks,
Vic
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I can't help you on the #'s but if you swap it, check your O.A. width, the distance between the spring centers, size and number of splines on the input shaft, or U-joint size, and brake line fitting size. Know all the dimensions before you shop (or know someone who knows!) LD

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Without researching too hard i can tell you that the front diff is a Dana 44 and I'd swear up n down that's a Corporate 10 bolt n the back.
--
Mad-Dog
'79 Chevy K-10
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I agree on the Dana 44 on the front, but the rear DEFINATELY is an Eaton w/ it's drop 3rd member and a round rear cover. Can't tell you if it's a h052 or h072. I'd leave it though until you actually broke it. those eatons had like a 12.5" ring gear on them, though the axles were only 12 spline.
hth, Bret
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http://www.67-72chevytrucks.com
click on message board/forum
67-72 message board and the 4x4 section
-dt
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