A tappet assembly (38; 138; 238; 338) for use in translating force between a camshaft lobe and a fuel pump assembly via reciprocal movement within a tappet cylinder having a guide slot, said tappet assembly (38; 138; 238; 338) comprising: a bearing assembly (56; 156; 256; 356) having a shaft (64; 164; 264; 364) and a bearing (66; 166; 266; 366) rotatably supported by said shaft (64; 164; 264; 364) for engaging the camshaft lobe; an intermediate element (58; 158; 258; 358) having a first aperture (68; 168; 268; 368), a shelf (70; 170; 270; 370) for engaging the fuel pump assembly, and a pair of arc-shaped bearing surfaces (72; 172; 272; 372) rotatably engaging said shaft (64; 164; 264; 364) when said bearing (66; 166; 266; 366) engages the camshaft lobe and said shelf (70; 170; 270; 370) engages the fuel pump assembly; an annular body (60; 160; 260; 360) having a second aperture (86; 186; 286; 386) and at least one stop member (88; 188; 288; 388) abutting said intermediate element (58; 158; 258; 358) so as to align said first aperture (68; 168; 268; 368) with said second aperture (86; 186; 286; 386), said tappet assembly (38; 138; 238; 338) further comprising; an anti-rotation clip (62; 162; 262; 362) disposed so as to extend through said first aperture (68; 168; 268; 368) and said second aperture (86; 186; 286; 386), said anti-rotation clip (62; 162; 262; 362) cooperating with said stop member (88; 188; 288; 388) so as to substantially prevent rotational and axial movement of said intermediate element (58; 158; 258; 358) with respect to said annular body (60; 160; 260; 360), wherein said anti-rotation clip (62; 362) has a guide portion (96; 396) for engaging the guide slot of the tappet cylinder, and a pair of legs (98; 398) extending from said guide portion (96; 396) through said first aperture (68; 368) and said second aperture (86; 386) so as to simultaneously retain said intermediate element (58; 358) to said annular body (60; 360) and align said tappet assembly (38; 338) with the guide slot of the tappet cylinder, and wherein said second aperture (86; 386) of said annular body (60; 360) has a second aperture width (102; 402) and said guide portion (96; 396) of said anti-rotation clip (62; 162; 262; 362) has a guide width (104; 404) greater than said second aperture width (102; 402). a bearing assembly (56; 156; 256; 356) having a shaft (64; 164; 264; 364) and a bearing (66; 166; 266; 366) rotatably supported by said shaft (64; 164; 264; 364) for engaging the camshaft lobe; an intermediate element (58; 158; 258; 358) having a first aperture (68; 168; 268; 368), a shelf (70; 170; 270; 370) for engaging the fuel pump assembly, and a pair of arc-shaped bearing surfaces (72; 172; 272; 372) rotatably engaging said shaft (64; 164; 264; 364) when said bearing (66; 166; 266; 366) engages the camshaft lobe and said shelf (70; 170; 270; 370) engages the fuel pump assembly; an annular body (60; 160; 260; 360) having a second aperture (86; 186; 286; 386) and at least one stop member (88; 188; 288; 388) abutting said intermediate element (58; 158; 258; 358) so as to align said first aperture (68; 168; 268; 368) with said second aperture (86; 186; 286; 386), said tappet assembly (38; 138; 238; 338) further comprising; an anti-rotation clip (62; 162; 262; 362) disposed so as to extend through said first aperture (68; 168; 268; 368) and said second aperture (86; 186; 286; 386), said anti-rotation clip (62; 162; 262; 362) cooperating with said stop member (88; 188; 288; 388) so as to substantially prevent rotational and axial movement of said intermediate element (58; 158; 258; 358) with respect to said annular body (60; 160; 260; 360), wherein said anti-rotation clip (62; 362) has a guide portion (96; 396) for engaging the guide slot of the tappet cylinder, and a pair of legs (98; 398) extending from said guide portion (96; 396) through said first aperture (68; 368) and said second aperture (86; 386) so as to simultaneously retain said intermediate element (58; 358) to said annular body (60; 360) and align said tappet assembly (38; 338) with the guide slot of the tappet cylinder, and wherein said second aperture (86; 386) of said annular body (60; 360) has a second aperture width (102; 402) and said guide portion (96; 396) of said anti-rotation clip (62; 162; 262; 362) has a guide width (104; 404) greater than said second aperture width (102; 402).