Yes, it's an aftermarket device that you can put on.
They are very popular for motorcyclists.

They make a device that you can attach to the wiring itself
and they also make bulbs that have the flasher unit built in
to the base (bulb swap only, no wiring).

If someone doesn't post a link for one before hand, I'll
post a link to one for you. I'll have to look in the
catalog to see who has one.

1995 Trooper LS auto 3.2 DOHC /w SOHC intake
1989 Trooper 2.6 auto
1989 I-Mark RS DOHC 1.6
1991 Stylus XS DOHC 1.8