Got an 04 s40 vin 68. Wondering if a vin 52 engine would operate correctly in place of the 68.

 

doing some quick research, the 52 code points to the B5254T4 (aka T2-R) and the 68 refers to the B5254T3. The biggest differences between the two engines are the turbo/exhaust manifold design and that the 52 has dual VVT where the 68 is single VVT. I've seen where people have done the swap but have adjusted the cam timing and leave the VVT unplugged (then again their goal was 400+ HP ). You may have some issues with ECU and fault codes as I suspect they use different ECU set ups. May take some more reading but you can google on the engine codes to get some insights.