It appears that following the recent service change on Teesside, the Sunday workings have been revised - with the 36/37/38 now interworking with 12/39 as followed:

37 xx28 Boro-North Tees Hospital xx00
37 xx07 North Tees Hospital-Boro xx40
39 xx48 Boro-Park End xx06
39 xx06 Park End-Boro xx23
12 xx30 Boro-Parkway Centre xx03
12 xx03 Parkway Centre-Boro xx36
36 xx43 Boro-Hartlepool xx45
36 xx51 Hartlepool-Boro xx55
39 xx08 Boro-Park End xx26
39 xx26 Park End-Boro xx44
12 xx50 Boro-Parkway Centre xx23
12 xx23 Parkway Centre-Boro xx56
38 xx58 Boro-Glebe xx27
38 xx38 Glebe-Boro xx10
36 xx13 Boro-Hartlepool xx15
36 xx21 Hartlepool-Boro xx25

The third hourly trip on 12/39 (the xx30 12 and xx28 39) remain separate