RAM upgrading question

Greetings to all, here I am again asking a serious but somewhat silly question about RAM. I have a T43 2687DDU (512MB) and am thinking about upgrading to 1GB total so I am buying another 512MB memory. Although I originally thought about buying an additional 1GB and make it 1.5GB, don't need that much of speed, plus it costs me around $100 so I decided not to. But in stead I'm gonna go for a 512MB.
I know from a fact that P/N: 73P3842 is the one for my T43, but this guy at a local computer shop says he has a 512MB for $20. According to him, it came off an used T43. He doesn't remember whether it came off a 1875 or 2687 or whatever number is was but it was off a T43.
Here is my question.
Does any memory that's off a T43 work for my T43 2687DDU?? I've been reading webs and all I've seen so far have a specific P/N but this guy only says it came off a someone's T43. I'm not sure if any T43's memory would work for my pc. Anybody have an answer for my question or any suggestions, I would appericiate.

Thanks

 

The same RAM standard, such as DDR2, are used on many notebooks. I can't think of a reason why the RAM from another T43 shouldn't work on your T43. By the way, I understnd you have 512 MB in your notebook, however, are you sure this is one module of 512 MB density, or two 256 MB modules. If the latter is the case, then you may just want to consider a 1 GB module, to make the total RAM count 1.2 GB. This will givee you quite an upgrade from 512 MB. Hope this helps.

 

Zero thanks for the response, I'm guessing that different RAM would work for my T43. btw I did check on my system and there is only one module of 512MB, so another 512MB is just enough. thanks