hi,

see ssc junior engineer or rrb junior engineer questions difficulty levels is diploma standard, where there is less of numerical questions and most questions are from theoretical basis, so studying of three years diploma syllabus is enough to crack, also in ssc je or rrb je the primary qualification needed is diploma , where b.tech candidate may also appear in exam. as per the qualification and eligibility criteria, you do not need to pass b.tech to appear in the exam. however apart from technical questions, there is non technical questions also from current affairs, numerical aptitude, reasoning, which also need to good score to crack the part 1 of the exam.

hope you may understand.