front seal almost definitely. R and R of a tranny is expensive for a $3.00 seal. I would try a pint of stopleak and fingers crossed. It should delay the R and R for a while at least until the rebuild.
m

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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)