I just installed a th-350 in place of my 700-r4, and my speedometer seems to be off around 20 miles an hour. Is there a new speedo gear or something I can order to get it to read the correct mph? Where can I order this? Thank you

 

gm parts, don't know what color you need

 

I know there are a BUNCH of you guys who have switched from a 700r4 to a th-350. And this would make all of your speedometers change, so can you please tell me how to get my speedo reading right again? specific parts please!!

 

If you can get a Buick, Olds, Pontiac th350 tailhousing with a 2 inch speedo housing hole you could simply use all of the speedo parts off the 700.
But if you can't find one you'll have to start from scratch.
You'll need your exact rear gear ratio, rear tire diameter and speedo drive gear size. Go here and figure out what you need. http://www.tciauto.com/tech_info/speedo_gears.htm with their speedo calculator, you may need to change your drive gear to find a combination that works. Repost here with the specific gears this site tells you to get and maybe someone could give you part numbers. Someone here gave me part numbers for the gears I needed, it's a lot easier to go to the GM dealer with part numbers.
No one can tell you what you need with the information provided.