If you not opposed to a non-stock appearing dipstick the locking ones sold by Mancini have a better design seal similar to what is used on current mopar trans dipsticks... Also basically the design used by BM for years... It doesn't leak... I have in the past bought a new dipstick & cut the bottom couple inches off & cut a like amount off the original dipstick tube then welded the new section on the old tube to keep the original look... Lotta work but it stops the leak & keeps it looking stock...

http://chucker54.stores.yahoo.net/man727diptub.html

"The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."