how to change a speedo gear on a 87 mustang

[bhrp]

i have a 88 gt 5 sp. 302.. i put 3.73 in the rear and it seems that the speedo runs about 120 at 60 mph.
anywhere i can get the gear and hoe hard is it to put in.

[rednotch]

http://www.ddperformance.com/Speedometer%20Chart.htm find out what gear drive you have in the transmission then order the right driven gear.... takes about 10 mins to change after jacking the car up.... only one 11mm bolt