The output shafts are the same size, unless you've upgraded to a HD SYE with a 32 spline shaft, but I don't know what years yours is. I'm assuming it's a 231? One thing to be careful of is removing the rear case half without breaking the oil pump. There is a pick up tube at the bottom of the oil pump, and this tube needs to be slipped (pryed) out of the oil pump housing before you pull the case apart. If you don't, the tube can break the lip off of the small recess that it fits into, requiring a new pump ($45). The rest of it is very straight forward, just unbolt and remove things in their obvious order, remembering so you can put it back in the opposite order. Look at the big shift ring so you know which way it is facing, so it goes back in the same way.
I have had the t-case apart both in and out of the vehicle, and I will always do it out of the vehicle. You are six bolts away from having it out of the rig and being able to work on it on the bench.......much easier. I guarrentee that's it's harder to split the case and work on it while under the rig than it is to remove the case altogether. If you remove the crossmember and let the t-case and trans hang down on the motor mounts (it won't hurt them), there is plenty of room to easily get to the top couple of t-case bolts to remove the whole case. The only one that's a PIA is the one behind the exhaust, having a shorty wrench makes it a little easier.
Here are some very basic instructions. Remove both driveshafts, pop off the linkage from the t-case, remove the crossmember, remove the trans mount, remove the speedometer cable and shift vacuum lines, remove the vent line, remove the linkage bracket, take out the six bolts to the trans, pull the case back and out. On the bench, drain oil, now remove the front yoke, remove the speedo sender, remove the rear yoke (SYE) and/or tailshaft housing, slip the oil pickup tube out of the bottom of the oil pump (oil pump is sort of thin aluminum disc at back of rear case, around the shaft), remove all case bolts, find slot at edge of case and use small pry bar or big screwdriver to split the case, pull back. Slide the output shaft, chain and sprockets, and front output shaft out as a unit, then remove the chain. Remove the gears, synchros, and sprocket from the old output shaft and put them on the new shaft.
I'd highly recommend replacing the plastic tabs on the two shift forks while you have the case apart, there are three on each fork. They cost only a couple of bucks and new ones are good insurance against a future shifting problem if they wear thin. Apply silicone to the front yoke splines when you replace the front yoke. Everything goes back the same way it came apart, again remember the oil pick up tube and be sure that it is in it's little hole in the oil pump, and that the oil pump is engaged on the splines on the output shaft before replacing the tailshaft housing.
Hope this helps........have fun,
