[smbrouss70]

BTW, this explanation from Livrat sounds like the easiest way to correctly locate the holes for a 4x4 to 2wd swap. I don't know if you have access to a set of front framerails off of a 2wd truck though.

Originally Posted by Livrat

The swap is a fairly easy one to do... I have done 6 of them in the last 20 years.. Mainly because I like 2WD blazers plus they are rare and are worth way more than 4X4's.. (at least here in WA)
The simplest way is to aquire a 71/72 2WD donor truck.. You will need the entire front crossmember assembly... all the brake lines... steering box.. motor mount towers.. shift linkage...(BB and SB are different)... radiator core support brackets... transmission crossmember.. and ... make sure to keep all the nuts and bolts.
Remove everything you can unbolt from the frame on the 4X4.. Get yourself a big hammer and chisel.. and knock the rivets out of the front spring hangers/core support brackets.. same with the rear spring hangars and outer shock plates... and remove..
I have found if you cut the donor trucks frame rails off at the firewall.. cut them into three pieces lengthwise at the corners, You can litterally bolt them on top of the frame on the conversion truck to line up the holes that need to be drilled... use a transfer punch to mark them... (available at most tool stores) then start drilling.. be prepared for alot of sweating..... then you should be able to bolt the 2WD front suspension crossmember and steering componets in and have the truck back on the ground... Bolt on the front radiator core brackets.. and all brake lines... slide the 2WD trans crossmember between frame rails close to where it should go... Whew.. by this time the hardest part is over... and you should have a steering and stopping truck...
For the engine mount towers I prefer to use the 72 style ones because they are stronger than the 67-71 ones.... since they are fairly expensive and you are at this point into drilling holes.. I opt to get them out of the 73-80 trucks.. BUT there are more than one style and you need to get the correct ones.. One will make your engine sit up too high... I can draw a picture of the style you need if you decide to go for it... (not sure exactly which truck/engine combo I get them from.. I just know what ones to look for..)
Depending on which engine/trans combo you will use you may or may not have to drill the holes for the engine towers.. I prefer to use a bare block and transmission assy and "mock it up' into the truck.. the lower bolts on the engine tower will usually just "line up"... again transfer punch the holes and drill then bolt them in.. On the transmission crossmember I like to use a 10inch long drill bit to drill both top and bottom holes at once... then bolt all together... On the trans shift linkage again.. you may or may not have to drill holes for the frame bracket.. will have to mock it up to see..
On to the rear end...
if the 4X4 is not a 69 ...(69 rear ends are narrower than the rest)
I opt to just put the 4X4 rear end on top of the leaf springs with either a flip kit.. or by welding on new spring perches.. I use "Moroso" spring perches for a Dana 60 which have the same tube diameter... If you are not a welder and are not familiar with setting the "pinion angle".. a flip kit would be the preferred method.... Then I use the axles and brake drums off the a 2WD to get the 5 lug pattern... Its a straight swap... You can use Axles/brakes from any 2WD 1971-80 12 bolt...
IF you decide to go ahead... feel free to email me and ask any questions... I love to talk trucks.. Just dont like working on em anymore...