I recently had a used transmission put in my tahoe due to the old one going out the guy also replaced the front seal and now a week later after parking it i come outside to see that all the transmission fluid has leaked out. wasnt home long maybe a hour or two. theres no fluid in it anymore. i dont know much about transmissions so i dont even know where to start to figure it out. im broke at this moment so cant have anyone come check it out yet so i was wondering if anyone could tell me how to check it out and what to look for etc to figure out what it could be i know i also need to replace two donut gaskets on my exhaust possibly the catalytic converter not sure. could that mess it up? any advice would be great thank you