Can some mechanic out there tell me the labor time to replace a tranny pan seal and filter on a 99 Nissan Altima? Also, is there any free laboe time guides on the internet for future similar inquiries?

Outfits, such as AllData, charge repair shops big bucks for that data. I doubt that information is available for free. I think I could drop and clean the pan and magnet, replace the filter, install a new pan gasket, and refill with ATF in 90 minutes.

1.7 hrs. Try your public library and see if they offer online auto manuals. Otherwise, nobody is going to have that info for free.