can anyone help as we are looking for a 0-24volt DC Rehostat and having trouble finding one

 

Rheostats are essentially a length of resistance wire wound onto a ceramic former.

 

Rheostat's are usually defined by Ohms & Watts capability.. [Variable resistors that can handle Power]
Do a google search.... there are thousands of hits.. Here's one from eBay:

Vishay Angstrohm Rheostats for sale | eBay

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