I need to get a workshop manual for my Cressida 1987 with the 5GE motor

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There will be various options, Toyota genuine manuals and after-market publisher brands such as Haynes..sounds like you have maybe an MX7# series Cressida.I cannot say for sure the Toyota factory ones would still be in print available new from dealer, but even if not, probably not difficult to get used on ebay.Bear in mind Toyota have always separated the manuals for their vehicles, one for engine series , one for chassis. body, electric etc, often there are supplements for emissions etc. You basically pick and choose from the sets as befits the car and as required. Or you could keep it simpler with an after-market one such as Haynes. I would not anticipate any of them being that hard to get,either new or used, even on a 30yo car like that.