It looked like it was leaking around the TQ seal, but I cant be sure.
It was wet in the center to bottom fanning out from the input shaft.
I'm sure it's transmission fluid. I have worked on my own cars for 30+ yrs. Transmission's are the only thing I never touched because of the fear factor, getting in over my head. Chevy was my car of choice in my youth. Did engine rebuild's rear end rebuild's and a total restore of the classic 69. Always had the transmissions done by a pro. I live in an area far from the city now.
That's a bench top quote. I'm sure I also need to add the cost of a new TQ, not sure about that he does rebuild them also.
Other concern's I have is the input shaft being worn to the point of allowing excessive fluid to get to the TQ seal location or the TQ being worn to the point of being out of tolerance or being cracked. Was even asked if the bell was cracked by the guy at the transmission shop. This all started out of the clear on my way home from work. Stopped to get appt. for the windshield to be replaced after an inspection the day before. Pulled into the driveway at home and noticed it leaking. Wasn't seeing the smoke cloud on the way home like I do now and the drive is 45-50 min. from home. Now it has the cloud at 70 mph. within 10 min. I'm puzzled and tempted to do the rebuild my self because I don't have $1,800.00 to pay someone to do it and would need to wait till next year. I would need the truck in the winter when the weather get's bad. I was watching a video about valve body's and seen a piston valve that releases excess pressure at the higher RPM's, it releases this fluid to the pan. The thought is this might be stuck in the closed position. I need to mention that I neglected the fluid for a period but found no metal particles in the pan that would alarm me. I did however find a piece of a snap ring on the magnet, that concerns me. It was only one piece about 1" long and flat so I only assume it's the defect mentioned by many others who have rebuilt these things. This has been rebuilt but I can't say when, I'm the 3rd owner of the truck it has 220,000 miles on it now. The guy I bought it from left it sitting in the driveway because he couldn't afford the gas to drive it anymore and it had 188,000 when I bought it from him.
If you found snap ring then you are going to need to rebuild the overdrive assembly.
Like I said 1800 is not bad, I see allot of clowns charging 2500. Quite honestly most transmissions only need new seals, some of the planet gears need to be replaced, and valve body upgrades. Other than that the clutches plates and discs do not really wear. Sometimes they do and yes you need a replacement, but that is generally from abuse and tolerance issues... Not actual wear from standard use (includes towing).
I rebuild these in my sleep, the automatic transmission is the simplest thing in the world. Right next to circuit boards, engines, digital cameras, and everything... Nothing is hard to do just do it yourself. These transmissions only go together one way (except a valve in the valve body).
Anyways, to solve your problem... I was thinking that it could be your torque converter that is leaking. Check the welds on the hub for any cracks, sometimes they develop a crack and will leak. If you want a service manual just private message me your email address and I can get you the factory service manual right away. It has pictures which is nice. I use it for checking tolerances and bolt torque specs... The actual rebuilding is common sense stuff. Hect even the tolerances are, but that is just from rebuilding them and what not.
If you do rebuild it yourself I can offer some assistance when you get stuck. I used to tell people what to buy to do a rebuild, but I couldn't be bothered. One cannot learn by being spoon fed everything, I can tell you where to buy and what you need at the very least, but when you open up the transmission and find all those little surprises things will change.
I wouldn't worry about cracking the bell housing. I have done that once. If you tighten the cooler fittings too much it will crack the bell housing because those threads are tapered threads, not straight threads.
As far as the rebuilders, listen to them but grain of salt. Half of them do not know what they are doing. Many people are going to disagree and that is fine... I rebuild them and started rebuilding them when I was 17 or 18 and they are just so simple to put together my god... Fun to rebuild! Especially the OD unit because you get to use a press and make your own tools for the press! (2x4 will be your best friend).
The only special tools to rebuild this transmission can be found at sears, lock ring pliers, snap ring pliers, wrench set, torque wrench, extension bar, hammer, seal remover, screw driver set,large c-clamp, and a press.
If the input shaft is worn it will not leak. The input shaft spins inside of the stator support. The torque converter hub slips over the stator support and goes into the seal. The hub engages into the pump gear's teeth. The stator support engages into the stator, and the input shaft engages into the pump blade inside of the torque converter. You could technically have no input shaft and it would not matter.
I would start to suspect a broken weld on the torque converter, and that is if the seal is not the issue. 
