I tried replacing my O2 sensors with the ones from atlantic british but the new ones won't thread in. The new ones also have a different head than the originals. On the Atlantic British website the pictures of the new ones are the exact same as the old but what they shipped was slightly different. I can't seem to find exact replacements. Any help what to get?

 

The photo shows sensor for '94 - '95 (14-CUX) with round plug, three wire. Maybe you got the '96 - '98 (GEMS) style, with square plug, four wire. Make sure you check the fitment years when ordering, photos can be misleading obviously.

 

Yes I got a Lucascux sensor from atlantic british not a GEMS but the threads are different than the original. The pic is of the old one and it threaded in and out easily but the new one keeps popping out when I try to screw it in.

 

Maybe try measuring the threads. Use a simple digital caliper (for example from Harbor Freight). Carefully measure diameters and thread pitches to compare old and new.

I notice the threads on the old one look shiny, like maybe was cross threaded. Use an inspection mirror to check the exhaust bungs. Might need to be re-tapped to clean up the threads.