98 speedometer questions

i have a 98 blazer LT and it needs a new spedometer. my friend who works at a junkyard said he could hook me up with one from a 2001. Ive heard you cant change the entire gauge assmebly out or certain things wont work, but if i was just to change the speedometer, would that work? any help appreciated, thanks

1998 thru 2004 Dash cluster will match, if yours has a tachometer, make sure the junk yard one has a tach also.....

well, the guy thats gonna give it tom me said certian things wont work, like the gas gauge