hey if i lift my 78 8 in. do i have to change the axels if im gonna go muddin its got 35in tires on it already..whats a good axel for that i dont no anything about axels

 

Your gonna want to find out what axles and what gear ratio you have. You can get this info from the axle itself. Look for a metal tag, also check for the build codes, usually found inside the glove box. You need to decipher the codes. Search for a code key online. It is probably a GM Corporate 10 bolt. Your gonna lose some acceleration running bigger tires without changing the gears in the axles. The bigger the diameter the tires, the more power will be sapped up getting them rolling. Don't forget bigger tires will throw off your speedometer & odometer. Go easy on it unless you are fimiliar with changing axle shafts.

 

well seein as how my spedometer and odometer dont work thats not a huge deal i got gmc 33 axelsn not danas i got the 10 bolt what kind of axel would be the best and cheapest upgrade what type of other vehicales interchange

 

so is it a 10 bolt front and rear or does it have a 12 bolt rear? Also what transfer case do you have?

If you would like to keep the current axles I would recommend changing your ring and pinion gears. try google for a axleratio/tiresize calculator to try and figure out how low you need to go.
If you really want to change axles I would look into using some 3/4 ton axles from a C/K pickup but you would need new wheels.