Most older service cars interior had a floor like any hearse or combo, with post cups or cot bar (sometimes flat floor with removable casket rack when needed) but the interiors were usually plain, with heavy duty fabric or vinyl.
Here are some more.
1962 Abbott & Hast Dodge service car
You beat me to that A&H one
All of the Abbott & Hast cars could technically be called service cars. Ron referred to them as "Junior Hearses"; never intended to be front line coaches, but slightly more distinguished than the usual service car. Most had permanently fixed landau bars, rather than a wreath like this Dodge. Duties ranged from removals to hauling graveside items to casket transport.
My Ford has the standard Ford station wagon interior, complete with fold down rear seat, but it had cot cups installed. Like John mentioned, in addition to the cups, mounting holes were added so a removable skeleton rack could be installed. The funeral home that owned this car kept the original rack unfortunately.