Autotrol Tank Adapter 1033064 ( new 255 series ) replaces 31N used on Series 155 models.
Comes with new style air check assembly, top of tank oring and 1.05" distributor oring.

If your old tank adapter is older than 1998, you will need to order the 13/16" bushing ( AP1001986 ) listed below, or replace your distributor tube with the new 1.05" O.D. size ( purchase the Bottom Distributor listed below, PN # MD1236 ).
Also, if your air check assembly is not the newer style used since 1993, you may need to purchase the 1/4" f x 3/8" c fitting listed below ( 584564NO ). A new oring kit ( AP150A144 ) is also recommended.
And don't forget the Locking Bar, which is also sold separately.