77 Transfere Case Operation
 

Picked up my 77 last week. I was trying out the 4wd and had some questions. The shifter pattern on the floor shifter for the T case has N in center. Below towards the back is High and High Lock. To the front is Low and Low Lock. From what I understand this is a full time case. My question is how does this operate. Is it always in 4wd or is the case always " live" and the axle is not locked in? And if so, am I correct in assuming that the lock designation on the shifter shows that the front axle is then live as well and turning?

I have also read about a conversion to eliminate the full time, putting in manual locks at the wheels. Ive heard this will limit the lubrication of parts in the T case but is a worthwhile mod. Has anyone done this swap? If so how much of a PITA is it?

the gold ol boat anchor np203 transfercase. ill try to remember everything its been a while since i had one.

basically these transfer cases work kinda like a differential. if you put manual lock outs in the front axle the truck will not move as all your power will go to the front axle as that will have the least amount of resistance. i guess you probably could and just leave the truck in 4 lock all the time but not sure

when you are driving it on the pavement you want it 4wd high. when you go offroad or in the snow you want it in 4wd lock as that will lock the transfer case into a normal 4wd set up where it locks the front end and rear end together . ive never installed the part time kit on the np203 case but i bought a truck where it was already installed so not sure what it takes to install it

anyone feel free to correct me or add onto it. i scrapped that truck in like 04 so its been a while

Everything above is what I've heard about 203's.
Part time kit has something to do with oiling of the chain from what I know.

So how hard would it be to swap in a different case like a 205? Would there be a difference in the linkage? Also is there a difference in the lengths of the front or rear driveshafts

unfortunately you cant just slap on another transfer case and be on your way. the 203 205 and 208 all use different adapters and different tail shaft lengths out of the transmission

when i took my 203 out and thought to myself i am not putting this thing back into the truck, i actually had to take my transmission out and send it into a trans shot and have the tail shaft changed to a longer tail shaft to fit the 208 i was going to use.

also they are pretty much all different lengths and all use different drive shafts and shifters so you would need to find a good parts truck and just swap over everything. the 203 i had had fixed yolks front and back the 205 i have sitting in my garage has a slip yolk so it wont work, though they do have 205s with the fixed yolks they just arent as common.

i did beat the heck out of the 203 when i had it in my first truck besides it leaking oil out of every seal on it it was a good transfercase. if it seems to be working leave it alone or wait til you blow it up then change it

ive got a 203 in my truck and its basically the first all wheel drive truck. unfortunatly ive got a mis matching gear set in the front and rear axles so i have to run with the front end lockouts open and run it in high locked. then its just like a 2wd. just sucks having to get out to put it in 4x4. soon to be fixed with a matching axle set!!!