98 Dakota Tran issues
 

I have a 98 crew cab 4x4 with the 3.9 V6. I've notice an occasional jerky shifts from 1st to 2nd and if I have driven for more than 45 mins the overdrive kicks out. It's like I turned off the overdrive. I'm getting a P0740 error code.
Does this sound like something that I can fix for a reasonable amount of money, given the value of the truck, or should I trade it off?
I do have an OK skill set when it comes to mechanics. I've changed brakes, water pumps, radiators, carbs, ect... but I've never gotten very far into an engine or transmission.
What do you think?

P0740 (M) Torq Con Clu, No RPM Drop At Lockup Relationship between engine and vehicle speeds indicated failure of torque converter clutch lock-up system. (TCC/PTU sol)

1st gear is by clutch, 2nd by band. I just had mine out of the shop and got to see it from the inside out- basically, the code says that the computer is locking up the convertor, but the engine speed does not drop as it should (~2-400 RPM), so it's obviously not actually locking up.

What color and level is the trans fluid? Granted, i think the issue is electronic, the losing OD (see similar topic down the listings) indicated a hydraulic issue.

I have a small leak so I top off the level every month or so. The color is red. I've had the truck for 2 years now and I don't know if the transmission has ever been serviced. I did change the speed sensor about a year ago.