Overdrive affect speedo reading ?

Hi guys,
I'm trying to get my speedo more or less accurate and I was just thinking,
I plan on getting an warn overdrive in the future. If you are IN or OUT of overdrive, does it affect the speedometer reading ? I GUESS it doesn't because the speedo is reading driveshaft speed, right ?
I just want to be sure.

Thanks !

 

OK, THANKS !
I was pretty sure, now i'm good to go. I just have to figure out how to get my speedo right. I just switched from 3.73's to the 5.38's. My speedo was right on with the 3.73's. I've got a 15 tooth "driven" gear, but not sure what the "drive" gear is. (probably 6 from what I've read ?) Now my speedo reads about 20 mph too fast.
I'm finding the gears are a bit hard to come by and finding the right one (enough teeth)may be difficult. I'm thinking a speedo ratio adapter may be the way to go.
Any thoughts ?
OR find a 22 tooth driven gear, are those available anywhere ?

 

Oh, it will definately affect the speedo.............it will let it go above 50 mph for once.

JB

 

Ha ha ha, yeah, I see my new "top speed" has just been reduced... Thus the need for overdrive...

One project is just the seed of another...