pontiac_ma04

Is it possiable to have messed up the welch plug on my 04 GTO when i was putting in the clutch kit and trans in...Heres what happended i had the trans out and put in brass fork bushing cause the nylon ones went out so got them in and went ahead and put a new clutch kit in as well.... got it moving and about 30 miles later i get a hell of an oil leak???? im new to LS1 and own 2 now all help is greatfull