What kind of fitting did you put on?

The reason I ask is that the high side port on my 1991 300TE did not have one installed either; I put on one made by Interdynamics, the kind Wal-Mart sells with the pink "permanent glue" to hold the thing onto the existing R12 service port threads.
I have had no luck getting a good tight connection to this port.
I've used both an Interdyamics and a US General (Harbor Freight Tools) connector to the high side guage set.
I know these aren't high end guage sets but I'm thinking that I should be able to at least get a gas-tight seal in order to read the high side pressure.
I just tried to get my current guage set (the US General /Harbor Freight Tools) to seat on the high side fitting with no luck, and now I have a partially exposed o-ring on the guage set's quick connect
Needless to say I'm not super happy with Interdynamics retro fittings.
I really want to be able to read the high side; I'm tempted to try to remove the Interdynamics fitting and see if I get a seal using the old R12 port to my guage set without the adapter, and next summer switching the system back to R12...

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Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic