The backlash is adjusted by thousands of an inch. I wouldn't trust my hands to do the measuring of that, you'll need a dial indicator. Also, these do wear in over time and you can expect a reliable .003"-.005" over the original adjustment. If it falls into that category and doesn't make any noise, leave it alone.
I don't have my parts book on hand right now to give you the number for the pinion seal.
Jeff
