Looking for expert to fix 3d printable files for truck cab

I have a truck cab file I purchased (STLs), it came in 3 pieces. The cab (a hollow shell), an interior (dash and seats), and finally the bottom half holding wheels/baseplate. There’s alot of uneven surfaces so when I 3d print them and try to assemble/glue, its difficult to match them up evenly and allow the glue to hold all 3 together. Need some help revising these files, mainly cleaning them up.