It should not be an issue, I am not 100% sure though. I had no issue swapping in a T5500 mobo into a T3500. Your motherboards look about the same, so it may very well work.
Dell Precision I replaced my T7600 motherboard with a T7610 motherboard with 2xXeon E5-2697 12 core processors and it worked! The only problem I ran into was the plug for the front panel USB/Power was on the lower right corner for the T7600 motherboard but Dell moved it to the middle of the T7610 motherboard so the cable was too short to reach. So we had to re-route the cable by taking is over the bracket where the front case fans were located and then everything fit. If you want some pictures of the cable move let me know.
I am doing this "mod" shortly, so yes, pics will be very helpful.
erik clod-svensson Here is the bracket I was talking about. That 3 cable set in the middle of the picture are the cables that control the front panel USB ports and I think also the system power switch. On the T7600 the motherboard connector for this cable is located in the lower right corner of the motherboard, but on the T7610 motherboard that connector is located in the middle of the lower edge of the motherboard which makes the cable 5-6 inches too short to reach. We had to disconnect that bracket shown in the picture, pull the cable loose from how it was routed inside that bracket and route it over the top of the bracket instead. This gives the cable plenty of length to reach the motherboard connector at that point.