Speed sensor swap. 86 to 84 goldwing

Okay I bought a motorcycle thinking it was in 84 found out it was in 86 but I'd already purchased it already disassembled it my bad however though I still took the speed sensor off of the 86 and I put it on the 84 and my speedometer works now and miraculously all the letters light up on the dash now where is before you couldn't tell the difference between a 9 and an 8 because the letters were out.