TOPIC:

i going to replace my tail light and the light bulb for the instruement cluster with leds. Does anyone know what size i need? i did a search but didn't see anything

If Im reading your intentions correctly, that you are changing the instrument (idiot lights) bulbs for LED's you have two choices.
Im assuming KZ1100 instrument light bulb and circuit are going to be similar to other Z's of the 70's era which means the instrument brake light bulb acts also as a power outage / bulb blown indicator. If it is the same or similar there is a power outage unit in the circuit which "reads" the resistance to see if your tail/brake light bulb is operational and if it isnt the instrument bulb flash's.
A straight swop will not work as the unit will believe there is an issue and the instrument bulb will remain alight all the time regardless of the if the brakes are applied or not. You will need to "fool" it into thinking the bulb is the normal filament type.
So.……
you need to either find an LED with a built in resistor or build in a resistor in parallel to the new instrument LED to get it to function correctly.

If your wanting to swop the actual headlight and tail lights for LEDS then the head light is no problem but the tail light will need a resistor as described above but in parallel with the tail light bulb or the instrument bulb will remain lit continuously.

If you didn't mean either of those things then ignore my ramblings

No that what i talking about. I already have all the turn signals replaced with leds and new flasher so they will work. i have 7 inch truck lite that i will be install this week. so all i have left is the tail light and he idoit bulbs like you stated.

I installed heavy duty Eiko 1891 bulbs w Miniature Bayonet Base from the auto parts store, so that's the type of base you'd probably need. I don't know exactly what 1100 you have, so I'm just assuming yours are the same as my 1981 KZ650-H1. I used them for the meters and pilot socket assy. The 1891s are longer than the stock bulbs, and the LEDs I've seen from superbright.com are kind of tall, but others have used them with no problems.

Eiko 1891 mini bayonet base