I looks to me that all 800 series bulbs have PGJ13 or PG13 bases except for the the 891 which is a PG4 or "bi-pin." From that aspect, I'd say that the other person was correct except for the 891.
In any case, the spot lights which we discuss here use larger automotive type bulbs and ballasts so there isn't much info about the 800 series bulb floating around here. The 800 series is generally used in fog lamps and driving lights so the options will be more limited than say....a H4 headlight conversion.