Complex sentence: There are 2 major RB26DETT blocks; standard block (code 05U) used in standard GTR models, and N1 block (code 24U) used in the R32 Nismo, R33 N1, and R34 N1 models.
Split into simpler sentences: There are 2 major RB26DETT blocks, There is standard block (code 05U) used in standard GTR models. The second block is the N1 block (code 24U) used in the R32 Nismo, R33 N1, and R34 N1 models.