1st Gen 5 lug Manual Transmission Leak question

Hello everyone, just picked up a 2003 1st gen 2wd Tacoma. I'm the 8th owner of this truck and didn't get too much maintenance history on the truck when I bought it so I'm in the process of changing out all of the fluids to baseline the truck. The truck itself has approximately 145K miles and is in pretty good shape. Lived in Socal and Arizona all it's life so no issues with rust or corrosion. I was changing out the manual transmission fluid and noticed this on the manual transmission housing. Wondering if the seal on the transmission is going bad. Also wondering how involved of a job it would be to fix the issue if anyone has had to deal with it before?

 

Looks like either the engine rear main seal or transmission input shaft seal. Both would require dropping the transmission to replace. The rear main seal is probably the easier of the two jobs. Does the fluid seem like engine oil or transmission oil?

 

It doesn't smell like gear oil and looks to be engine oil. I get a drop or two whenever I leave the truck parked overnight and the engine oil level doesn't seem low. I cleaned off the bottom, in the process of slowly cleaning out the engine bay so I'll have a better idea of where it's coming from.