Repair Heater Core Nipple?

[sierraingws]

I have searched, and found a reference but not sure on deatails. 99 Sierra 2500. 200K. One of the heater core nipples at the fire wall broke off, right at the firewal, when hitting a bump. It appears to be plastic. I am assuming this is directly connected to the heater core, but I have never seen a plastic nipple on a heater core before. Is there a technique to repair that nipple without removing the core? It appears the core is fairly inexpensive, but the one reference I found on core replacement said a multi-hour job to get old core out.

 

To recap: Is is possible to do anything with the broken nipple?

Difficulty of R and R of heater core?

 

Of course this happened driving up Vail Pass. Amazing what can be found to facilitate roadside repair.

 

Thanks