TE probes

I suspect that a repair I did recently on the TE probe on my DG 800B
didn't work. So it's time to get a replacement. My factory probe is
8mm but the end that fits into the receptacle has a small reduced
diameter section (4mm) that must fit into a reduced diameter hole
inside the receptacle. My previous gliders didn't have this smaller
section. So my question is, does any replacement probe have to have
this arrangement, or can I just plug in an 8mm probe if it seals
properly?. I'd like to get it right cause these things aren't cheap.
Thanks, Tim