Could you try with the latest gdb-6.7?
http://community.qnx.com/sf/frs/do/listReleases/projects.toolchain/frs.gdb

Thanks,

Aleksandar

After rereading your post, I don't think you can get any useful results the way you are trying to: it is highly likely 
that between SP2 and SP3 there were changes in shared libraries. It is sufficient to have one function changed and 
everything in the library can be shifted. 

Core is basically a memory dump. Therefore, even the slightest difference in binaries that generated the dump 
(executable + shared object) will make core next to unusable (in terms of debugging it with gdb). Example: core 
specifies current instruction pointer; gdb uses that to lookup binary it has (let's assume its somewhere within libc); 
if libraries differ, what gdb finds will not correspond to what was there on the target. The same applies to unwinding 
process, it will use stack pointer and memory dump from the core, but all addresses will be looked up in local shared 
libraries, in your case SP3 ones which will very likely have something unrelated at those addresses.

Therefore, what you absolutely need is *exactly* the same binareis. Luckily, you do not need to build everything on your
 machine, you can get all the shared libraries involved from your customers' machine, including core and the binary 
causing the core. Having all that in place, you should be able to get meaningful results even with gdb-5.2.1

Hope this helps,

Aleksandar