Transmission grinding

Hey there everybody, new member here but have been reading this forum for a little while. Alot of great info floating around in here.
Last week i bought 2 tacomas. one running and driving and one parts truck for $2800. The running one has a manufacture date of 08/95 so i assume it is considered a 96. It runs fair but still has some idle issues and likes to drink gas but the thing that bothers me about it is the grinding gears. It had a new clutch installed when the previous owner swapped transmissions with the parts truck. It would grind through all gears a little unless you pump the clutch between gears. Shifting from 1st to 2nd and 2nd to 3rd is the worst. Down shifting, there is nothing i can do to make it not grind. i bled the slave cylinder and replaced it when that didnt help just to still have the same issue. I have changed the oil which was pretty bad. I am thinking it might be something in the transmission?

Anybody have any more suggestions? Thanks in advance!