Rear end seal ,i have a new seal but dont know which end goes in it is different from orginal

Pinion seal. It's pretty common. http://youtu.be/Z0zz1_4UYqk

The rear end seal.first block the wheels,so truck does not roll away.remove drive shaft four bolts to do this.might have to a pry bar to seperate .then take a center punch and make a mark on the nut.then mark the yoke.with a mark.this is done,so when its put back together,you dont over tightn the crush spacer.then remove the yoke.have a pan under neath to catch any rear end oil.remove yoke,then remove seal.reinstall seal,and reverse the process.hope this helped brad

Remove the rear diff cover (use a pan under there ...it's full of gear lube).Rotate the diff till you can see the pin that holds the spider gears in place. At one end of the pin, you will find either a roll pin or small bolt that retains it. Either drive the pin out or un bolt it (depends on what you have), then remove the pin. (careful when rotating carrier after it's out or, the spider gears will fall out. After it's out, DO NOT rotate the carrier or the same thing can happen. Dont turn the driveshaft or axle). Push the axle in and the "c" retainer on the axle will fall out. If not, help it a bit so it does. You can then remove the axle and access the seal.
After the seal is out, check to make sure there isn't any metal debris behind it. That indicates that not only the seal is bad but the bearing as well. Keep the new seal square with the axle tube so it goes in straight. Put some lube on the seal so it doesn't self destruct before lube reaches it. Remainder of the job is the reverse of removal. Don't forget to re-fill the diff before using it.

Replace the seal forthwith. leaking grease will wreck your brakes and that is dangerous.

Typically rear ends take 90 weight oil, it goes in through a plug near the center of the rear end, fill to bottom of the hole, with rear end level. You can get a suction gun to **** some fluid and pump into the rear end.

put flat pan under the housing remove the bolts holding the cover usually 10 or 12 (1/2 or #12 metric) bolts? allow the rear end grease to drain... then scape off the old gasket clean with brake cleaner spray install either new gasket or form one with oil resistant silicone put the cover back on , dont refill the fliud for at least 12 hours if using silicone. Also check the front driveshaft rear end yoke seal....they sometimes leak making the illusion of a rear end pan cover leak...if that is leaking you remove the shaft carefully...remove the large yoke retaining nut, replace the press in seal...be sure retaining yoke nut is properly torqued when reinstalling .

well if the axle is leaking you dont need to adjust the shims, it needs a new seal. pull the brakes off open the rear diff there will be a c lip holding the axle in, remove the c lip pull the axle repalce the seal on the end of the axle tube, put it all back together and you done

Not hard to do. You need to remove the drive shaft, to get to the nut that holds the rear yoke from the differential. Once the rear yoke has been removed, you can replace the O ring seal from the differential by using a screw driver to pry out the old seal. Try not to damage it to much so you can use it to help tap in the new seal. Once the seal is out place the new seal in place by hand and then place the old old seal on it and tap in the new seal with a small hammer. Take care to ensure that the new seal goes in straight and place some grease on the seal before you place the yoke back in to place. Tighten up the yoke nut and you may want to replace the U joint at this time too since it's off the truck. Once everything it back together, check the differential oil level and top off. Good luck and hope this helps, you can get the parts at Auto Zone and they can also give you the step by step instructions to getting the job done with common tools. The hardest part that i can see you having is the removal of the yoke nut, the job takes about an hour to do so if your going to have a garage to the job the most would be 1.5 hours but should take them about 30 min to do. 

Remember SAFETY FIRST. Jack up the right rear wheel, support the axle with a jack stand, remove the wheel, the brake drum, the banjo cover or differential cover. Allow the gear oil to drain out into you drain pan, carefully and slowly spin the ring gear (watch out not to pinch your fingers) look for a small bolt that is restraining the king pin, remove the bolt and then carefully slide the pin out !(don't spin the axles or ring gear while the pin is out) if you do the bushings and spider gers will move out of their places. After the pin is out then go over to the exposed axle and push it in until it stops. Go back over to the pumpkin and look inside, for a "U" shaped washer it will be on the end of the axle. Remove it from the axle. Now you can remove the axle and replace the wheel seal. Either rent a seal installing tool or carefully use a block of wood and evenly install the seal. If you kink or damage the new seal remove it and try it again. When you put everything back together put a little thread lock on the bolt for the king pin. dont over tighten it, could snap it. Let me know if I can help any more.

drain the fluid, take the old seal off clean where the old seal was with some brake cleaner. replace seal with a new one or the gasket sealer in a tube spread evenly put cover back on fill back up with gear oil up to the hole in the rear end

First, the easiest way IS to remove the transmission, it is a one piece seal, if it were a 2 piece, you would need to remove the oil pan and Rear Main Bearing Cap which in my opinion is alot tougher. When installing the new seal, make sure the the end of the crankshaft is clean of debris, lube the seal before sliding it over the end of the crankshaft to ease installation and some like to apply a thin coat of high temp sealant to the outside surface of the new seal to ensure no leakage. When reinstalling the flywheel/flex plate, proper torque is key because you dont want it working loose and having to remove the transmission again.