dont get robbed by either of them options, drop in to a local gearbox specialist and ask them for a filter. i got one for 15 quid from my local transmission specialist, the gasket is rubber so unless you damage it reuse it, the oil though im told must be the correct texaco texmatic. i did mine twice within a couple of months to flush it through, when you drain it you never empty it all as a couple more litres are held in the torque converter.