The headlights on the Esprit are 5 3/4“ round sealed lights (stock). A recommended replacement is the Hella e-Code lights. This isn't a simple “drop-in” procedure though.
One user notes:
Just upgraded my Headlamps on a 87 HCI
Hella71456 - Outside low / high beam - H-4 bulb – drops in conversion, no modifications
Hella 71156 - Inside high beam H-1 bulb… I had to cut off a male spade connector from the Esprits wiring and replace with a female. (one of the connectors was already female)