yes your truck has the printed circuit that does not have the tach in it.
realistically you have 3 options:
1- mount an aftermarket tach in another location
2- buy a replacement cluster with correct tach and gas gauge
3- buy the aftermarket tach/gas gauge in one that fits in the stock cluster (
http://gmsports.com/trucks)
I actually have one of each in different trucks and I can tell you IMO the original factory setup(#2) looks the best. that said, i don't know if you could get a factory tach in 86 still? so you might have to go with option 3 if you want it in the cluster. I have the combo tach/gas gauge in my 87 tbi truck and it works flawlessly.