Gentleman,
I have been without 3 of 4 for over a year now.
Dasgeek posted a possible fix without fully removing the running boards. (try a search for Dasgeek??)
I am pretty sure the post was Feb of 2014.
He says the Bulbrite 715210 - 10 watt T3 (found @ www.1000bulbs.com) works but is bit bigger in size than the #891 replacement.
If I can find the post again I will cut and paste here.
Regards,