I recently swapped my transmission. Where can I order a driveshaft to be made for my car? and how much will it cost?

 

You swapped from what to what?

 

I dont know what the original tranny was but now I have a Muncie m20 4-speed. The end of the original driveshaft does not fit into the tailshaft.

 

"The end" is called the slip yoke. Since that doesn't fit (automatic has more splines than the manual) your car would have had the T350. Your current driveshaft should be the correct length, you just need a slip yoke for a manual. But they're not exactly a dime a dozen. Do you know how to change u-joints? I found this shaft on ebay: Driveshaft
Count the # of splines on your output shaft of the trans, and verify from the seller how many his has.