Why is it buzzing by my tranny pan when i put it in gear?

You need to put your car on a lift and see exactly where the leak is coming from.
Wipe clean the bottom of your transmission use a degreaser and some shop rags so you can see what kind of leak you have and where its leaking at, I assume it is an automatic.
Is it a pan gasket, a seal or a cracked case.
I would take it to a transmission shop and
have them fix it or replace it. If it is a pan gasket you probably can do it yourself if your are up to it, depending on your skill set level, Youtube can help guide you if you decide to go that route.
Whatever you do please do not use any diy tranny sealant that you put in your transmission, it’ll gum up the internal gears, belts, ports and could ruin your transmission, if it’s just a pan gasket leak.
If its a seal a tranny shop can rebuild it or a crack case your tranny needs to be replaced with a rebuilt tranny or a certified salvaged tranny.

can put the truck in gear

if you are handy with a wrench. you may want to check the filter for the Tranny. its located under the pan. You will need to drain the oil.
it really doesnt sound like the clutch pack for the reverse is going out. Cause when they give out they normally just go...

drop tranny pan.which will drain fluid. replace filter, gasket then pan refill with fluid .start and let run a few minutes then put in gear it may take a second for fluid to get all thru trans that should do it

Buy a new gasket and screen. Get under there with a bucket and unscrew all the bolts holding the tranny pan up. Try to let one corner down first, so it drains into the bucket. It will be real messy. Put in the new screen and gasket. Be sure the bolt holes on the pan are flat. They get pushed in if tightened too much. Bolt up the pan again, tightening the bolts evenly and not too tight. Add six quarts of tranny fluid. Run it and check for leaks. That's it.

Well your clunking noise is most likely the u-joints the leaking pan is the tranny pan what you would have to do is get a tranny kit and change the pan gasket tranny filter and fluid or take to a shop and have a tranny service done.

first you need to get a pair of safety glasses to protect eyes from cleaner. then you need 12.6 pts or 6.5 to 7 quarts of transmission fluid+ filter.you also need a drain pan to catch transmission fluid.you need a 3/8 ratchette and socket set.you need some paper towel and maybe1 or 2 cans of brake cleaner.now you want to safely raise and support car on jack stands.make sure you are on solid level ground.put drain pan under transmission to catch fluid.take ratchette wrench start removing tranny pan front and side bolts.loosen rear bolts one turn let the pan drain.when all tranny fluid drain out of pan. then remove pan clean it good with brake cleaner.remove all traces of old gasket. from pan then dry with paper towel..then you remove tranny filter.becareful not to damage anythingthen put in your new tranny filter then.wipe and carefully clean around gasket area on transmission with paper towel.make sure there is no traces of olds gasket material on tranny area where tranny pan gasket seals.now get new gasket align its with tranny pan holes.you might want to buy a gasket adhesive.just put on some to hold gasket in place when you install it to transmission.besure to clean all tranny pan bolts real good with brake cleaner. then dry them off real good.because some transmission you have to put a little rtv sealant on bolts.to keep them from leaking.now once you get bolt holesand gasket on transmission pan line up.all tranny pans bolts with a little rtv silicone on threads and on bolts head where they meet the pan.then you transmission pan in place.make sure gasket and bolt holes line up.when putting bolts in dont tighten them until you get them all in first.when all bolts are in.then you tighten criss cross dont over tighten them. torque them to 90 inch pounds .when all is done .starting putting tranny fluid in.and check for leaks.start the engine up let it idle for few minutes if you see no leaks lower car down to ground.then move transmission gear selector through each range and back to park.make sure tranny fluid level correct before driving car. WARNING IF YOUR CAR DONT HAVE THE TRANSMISSION DIP STICK.AND HAVE A FILL CAP INSTEAD THE DEALERSHIP HAS TO CHANGE FLUID.BECAUSE THEY HAVE TO RAISE CAR ON LIFT TO CHECK FLUID LEVEL.BECAUSE CAR HAS TO BE RAISE UP LEVEL THEN A DRIP PLUG IS MOVED TO CHECK TRANNY FLUID LEVEL.

the is a drain plug on bottom of tranny. Remove all tranny fluid. Then remove bolts on the tranny pan, remove pan. Remove couple filter bolts and change filter. Replace new gasket and tranny pan. Fill up tranny with 8 quarts or whatever your user manual says with correct fluid.

first you need to buy transmission fluid new filter and new gasket.you need 11.4 pints of transmision fluid.raise front of vechicle.set parking brake.block both back wheels.besure support vechicle weight with jack stands. get a drain pan.if your transmission pan dont have a drain plug.loosen rear pan bolts a few turns.remove the front and side transmission pan bolts. let fluid drain.remove tranny pan. then clean old gasket material from transmission and pan carefully.dont scratch or damage surface.clean old tranny bolts using brake cleaner or buy new tranny bolts.you have to put a tiny film of rtv silicone on tranny bolts so they wont leak.carefully remove old tranny filter and put on new filter.clean all grease grim away from tranny pan it should be **** and span because.you might need a little gasket adhesive to hold gasket in place while putting pan back on transmission.to line up bolt holes.loosely put all bolts in you have to move pan a little to get holes line up.when all is finish put tranny fluid back in.besure you put 11.4 pints back in that about 6.5 quarts. make sure tranny fluid level is right before driving vechicle.l

in 2003 there shouldn't be a tranny dipstick? there is a fill plug on the front behind the metal shield(bolted to transmission).it should take just under 3L. OF VW TRANNY FLUID