I know this is an old discussion...
I was trying to do the same thing in WF5, but that solution doesn't work. I loose all the dimensions when the new or different part is updated in the drawing.
Does anyone have an update solution for that problem?
The solution Andrew Deighton posted was for a specific scenario. In Andrew's solution, you have to have almost a perfect storm of situations.
To briefly restate Andrew's advice - If you have a part called FRED.PRT and have saved it (using Save A Copy) to a new part called BOB.PRT, you can trick the drawing for FRED.DRW to use the BOB.PRT model instead without losing dimensions. This also assumes you're using neither Windchill nor Pro/INTRALINK... OR if you are using them, that you have the config.pro option let_proe_rename_pdm_objects set to "Yes" (normally this is set to "no").
If you are trying to replace the part in your drawing with a completely unrelated object, you're likely going to be stuck recreating your dimensions.
You will be able to swap parts in the following scenarios:
Otherwise you're likely to have to recreate most or all of your dimensions. If you can tell me a bit more about your situation, there could be other options. There are so many scenarios, it's hard to detail every technique for handling all of them. If you can help me narrow it down to your specific situation, that would help.