Old School Method

The first thing you need to do is pull the valve covers off the engine. You'll need a socket and a 3/8" ratchet. Loosen all the bolts till you can lift the bolt up. Don't bother removing the bolts from the valve cover. Once you got that the valve covers will come off. Just lift the 6 covers straight up.

Now you need to use your 1/2" ratchet and the 15/16" socket to rotate the alternator. You want to turn it towards the passenger side (or towards coolant bottle). You want to get the gear to be in the TDC (Top Dead Center) using the timing pin found under the injection pump.

Mopar's Notes

Once TDC found using the timing pin mark the damper and the gear case in one spot denoting TDC. There is a reason for this...

Now check the rocker arms on number 1 cylinder. both should be loose at this point. If not check both rockers on cylinder number 6. If cylinder number 6 is loose then your 360° out on the crank, so rotate another 360° till you line up on your TDC marks again.

WARNING! Be sure that the timing pin is pulled out of the gear before rotating the engine. Otherwise damage to the timing pin will occur!

Here is the valve clearance measurement

But if you followed my suggestion above now you wouldn't need to mess with that pin anymore! But for making things simple we'll start at TDC of number 1 cylinder with both rockers loose.

now rotate the engine crank 360° again so now cylinder number 6 rockers should be loose. Using your new timing marks on the damper.

Now reassemble the valve covers.