I don't have either but from similar models I have & held;
- the 4553TSW pre-rail has one round smaller magazine then the railed version (6 vs 7). Noticeably shorter.
- you don't say exactly which 3953?
The 3953 & railed 3953TSW are standard 8 round mags.
The 3953TSW pre-rail is 7 rounds mag.
The two pre-rail models would be of similar (shorter) length grips.
If it's either of the non-railed 3953s, they'll be longer.
The (7) round 4553TSW & the (8) round 3953 grip length are of similar length.
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The pre-rail 4013TSW & 4056TSW were shorter grips/mags too.
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4013TSW & 4056TSW (pre-rail)
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