axle shaft seal

knowing if its a 1/2 ton or a 3/4 or 1 ton would be helpful

You're lucky it's the passenger side....

Remove the center cap, then remove the cotter pin from the axle nut, and remove the axle nut (need a big socket for this - 1-11/16, I think). Loosen the lug nuts, then raise the wheel off the ground and remove the wheel. It will be helpful to get the driver's side wheel off the ground too, so that you can cycle the steering.

Remove the brake caliper by loosening the two 3/8" allen-head slide bolts. Tie the caliper up to the suspension so it doesn't hang by the brake line.

If this is a 1500 series, slide the rotor off.

Loosen the three (1500-series) or four (2500/3500-series) hub-to-knuckle bolts from the back side of the spindle. These are 14mm 12-point heads, so you need a 12-point socket. Back them out about 1/4" or so, then strike them with a hammer to "press" the hub off the spindle. Strike each one in succession. Once they bottom out, loosen them a little more, and repeat. Once the hub has come loose, remove the bolts, and remove the hub. If the axle comes out with it, that's OK. If not, remove the axle next. Pay attention to the orientation of the spacer ring and the brake dust shield.

Next, remove the CAD motor housing from the axle. It's held on with four bolts. Have a drain pan ready, because some axle fluid will probably leak out. Once this is off, you'll have access to drive the axle seal out (it's inside the axle, just to the right of the CAD opening). Put the new seal in place, and use a large socket and a long extension as a seal driver to drive it in place. Have a helper watching through the CAD hole to make sure you're in alignment before you start beating on it.

With that, lubricate the end of the axle with grease (so it won't damage the seal), and slip the axle back in place. Verify it's in position through the CAD opening, then re-install the hub, spacer ring, and dust shield. They're a little tricky to get all lined up at once. I use a couple of screwdrivers stuck through the mounting holes from behind, that act as alignment dowels. Get two mounting bolts (or 1 if it's a 1500) started, then remove the screwdrivers and install the others. Torque these bolts to 125ft.lbs. Slide the rotor back on (1500 series), and re-mount the brake caliper. The slide bolts torque to 30 ft.lbs. Put the axle nut and washer back on, and snug the nut for now. Re-mount the CAD (if the gasket came off in one piece, you can re-use it - otherwise get a new one, or use some RTV), making sure to align the shift fork with the shift collar.

Put the wheel back on, tighten the lug nuts, lower the vehicle back to the ground, torque the lug nuts to their proper torque (don't remember these off-hand - check your owner's manual - it should list the torque values), then finally torque the axle nut to 175ft.lbs. Install a new cotter pin (tighten the nut further if necessary to align the cotter pin hole - never back off a nut for cotter pin alignment), re-mount the center cap, and replace any gear lube that you lost during the process.

i follow you in every way except i dont reall know what the cad motor housing is could you explain thank you for all your help

It's the shifter assembly bolted to the back of the front axle, passenger side. It's got a round flying-saucer-shaped vacuum motor on the left, with a couple of vacuum lines going to it. This is what engages the passenger-side two-piece axle when you go into 4WD.