In general, spondylolisthesis is considered a yellow flag/precaution by some manual therapists. I would avoid mobilising the segment itself as any posterior to anterior force may bring the lumbar spine into more extension and causes pain/discomfort. I don't have any articles to support any type of mobilisation but emphasise on strengthening the anterior abdominal muscles and the core in general.
Dear Shakil, thanks for putting up this question in RG. As per my clinical experience YES relocation mobilization is benefit in Grade I & II Spondylolisthesis patients. Here the aim of mobilization is not to improve the ROM but to re-align the anteriorly shifted vertebrae. I have used AP glide using intra-abdominal pressure in almost 250 patents with grade I or II spondylolisthesis (L4 over L5 or L5 over S1). Till now I didn't find any adverse effect with this technique. When we applied the AP glide with correct dosage, many of patient achieved immediate pain relief, improve SLR range, bed mobility, gait and other ADLs. Therapist need to be very precise about the targeted vertebrae & its required dosage. Performing AP glide in such condition should be always with cautions. I do not have any published article to support my clinical experience.
Mobilization alone should not design in treatment protocol. Segmental Core muscle activation starting with Level-1 will always reinforce the effect of mobilization. Global core muscle activation may be added in following.