Ok the o-ring that is on the heater pipe on the manifold side. I have had 2 that has ripped apart trying to insert the pipe in. It’s a super tight fit on the ones I got from lucky 8. I have tried Vaseline on the o-ring and inlet on the manifold but still rips it apart.
so what am I doing wrong ?

 

wrong O ring...get one from Rover's North

 

The correct part number for that O-ring is ERR6434. Rovers North has it priced at $5.11 (plus shipping, I expect). Atlantic British has it for $1.95.

I too tore one or two when I put the top end of my truck's engine back together 10 years ago. I'm surprised the Vaseline didn't do the trick for you. Next time you might try soap to lube it up, since the Vaseline could cause long-term deterioration of the silicone O-ring.