The 0744 code is a torque converter issue. The 0732-0735 codes are incorrect gear ratio readings calculated by the computer comparing your engine rpm and trans output rpm, for gears 2-5, respectively. The 0615 code may be unrelated as it's a starter circuit code.
My guess is, you have low fluid, or you have contaminated fluid from a crack in the radiator mixing antifreeze and atf, or you have a trans valve body about to go up in smoke.
Check your trans fluid. If it's full, and looks like regular trans fluid, I'd guess valve body (which means a new trans, essentially, at your age/likely mileage). Antifreeze in the trans fluid means new trans. Low fluid means you may have a leak, or when it was last changed it wasn't properly filled. That may be as simple as topping it off, but it may have done enough damage to require a new trans.
And by new, I mean a reman. Don't waste your money on brand new. And compare the cost of a Level 10 trans to any local reman or rebuild you have quoted. The word is, Level 10 is the best Titan trans builder out there.
