Call Brewer's and get a gasket/seal kit #GS-23 (check your year 1st), it's like $20.00 or so and you can change the slip yoke seal, side cover gasket , 1-2 / 3-4 o-rings and the speedo o-ring without taking the trans out.
The front bearing retainer gasket, tail housing gasket & reverse o-ring the trans has to come out and apart...