Help diagnosing a slipping 700r4

Hopped in the '86, put it in gear, hit the pedal and it started moving but then started slipping. I didn't want to take it on the road for fear of not making it back home. So I don't know what it does as far as shifting. Couldn't tell if it was slipping in reverse.

I've put 70k miles on the vehicle since I've had it so I don't how many are on the trans. Last time I drove it (a week ago), it was perfect.

Pulled the dipstick this morning and I do see some black build-up - can't tell if it's anymore than the usual traces of residue. Normal??

I have a dash trans temp gauge and it has never even gotten close to overheating. Usually rides in the 140 range.

The fluid/filter was changed 17k ago.

I've got a transmission pressure gauge that connects to the transmission port but I need advice on what pressures to look for AND if this would help in diagnosing the problem.

Detent cable out of whack?? Haven't inspected yet.

What should I check first? Change the filter/fluid? I can road test in the neighborhood first.

TV cable seems ok.

Drain fluid and dropped pan. Found a loose filter! It didn't fall off but I could push it up and down a good 1/2 inch.

There were some metal fragments (1/16" size) in the bottom of the pan - not a lot but it was more than the normal fine black powder.

New filter, filled it up, test drove. Same symptoms: slipping in first and reverse when moving up my driveway. Drove down street and got a good 1-2 shift but it would NOT shift out of 2, at least getting it up to 30 mph. Seemed to also slip in 2 when I really gave it the pedal.

Any thoughts???

Last time really I drove it, it showed absolutely no signs of misbehavior. This just happened quite suddenly. I've had other 700's go out in the Sub and I guess it did just switch from good to bad suddenly.

:(:(:(

any thoughts anybody?

Metal junk is a very bad sign.

Sounds like something broke.

Possibly a sprag
Gonna have to come out I'm afraid.

Missy