Both the top and the bottom of 4890 are off by 1 LDU compared to the physical part. The current measures are also non-standard.
The top should be modeled as 4 LDU, which is slightly less than the 4.5 LDU of the physical part, but 1 LDU more than the current model (3 LDU).
The bottom should be modeled as 16 LDU, which is very close to the physical part (15.8 LDU), but 1 LDU more than the current model (15 LDU).
With these fixes, the slot height becomes 72-16-4 = 52, which is appropriate for the corrected drawer height.
If the 3 LDU offset is due to the top, then it should be increased to 4 LDU.
The top should be modeled as 4 LDU, which is slightly less than the 4.5 LDU of the physical part, but 1 LDU more than the current model (3 LDU).
The bottom should be modeled as 16 LDU, which is very close to the physical part (15.8 LDU), but 1 LDU more than the current model (15 LDU).
With these fixes, the slot height becomes 72-16-4 = 52, which is appropriate for the corrected drawer height.
If the 3 LDU offset is due to the top, then it should be increased to 4 LDU.