Fitted FLM XL Hybrid Bulkheads to FLUX, Dogbones Too Short?

I just fitted FLM40010 to my Savage Flux and the dogbones fell a bit short. They make horrible grinding noises and dislodge while steering once in a while. Since I've taken out the original flux cups (because they didn't fit the bulkhead) and put in FLM ones I'm suspecting (with the "XL" branding at the kit itself) I need XL dogbones. Am I right?

I've just learned that the dogbones...well driveshafts for the FLUX and XL are the same (HPI 86246) What in the name of St. George??? Do I need some kind of springs inside the cup?

[_paralyzed_]

a small piece of fuel tubing, or an o-ring in the drive cup will help to keep your dogbones centered and in the cups.

We solved it using the fuel tube method. For how long it will hold I wonder...

I installed the FLM arms on my DB-17 Savage Flux and the dogbones were too short. They locked up and wouldn't move unless i shook em loose. I had to put some tubing in there. Haven't tried driving it yet.

What's up with that?