Early model dipstick tubes used an O ring about 1/8" thick by about 3/4" diameter. Later, the shape of the tube was changed, and a rubber sleeve about 1 1/2" long was used as a seal. To switch from the O ring to the sleeve, you would need to change the dipstick and the tube to the later model items. The sleeve seal does a MUCH better job of preventing leaks!
Jerry
