A gas turbine engine comprising: a combustor section having a diffuser case (204; 304; 504) with a diffuser case flange (204a; 304a) and a case support (324, 552); a turbine section arranged aft of the combustor section along an engine central longitudinal axis, the turbine section having turbine case (206; 306; 506) with a turbine case flange (206a; 306a); a connection (202; 302; 502) wherein the diffuser case flange is connected to the turbine case flange; characterized in that: the case support extends radially inward from the diffuser case and extends in an axial direction to provide a forward end engagement; and by a heatshield (322; 400; 522) engaged with the forward end engagement, the heatshield comprising: a metal body having a first end, a second end, a first side, and a second side, wherein the first side and the second side define parallel sides extending from the first end to the second end; an engagement portion (326; 414) formed along the first side and engaging with the forward end engagement of the case support; a shielding portion (330; 418) formed along the second side, wherein an air gap is formed between the heatshield and the connection, with the air gap having an aft extension of the air gap between the shielding portion and the connection, the aft extension extending to an edge of the second side; and a mid-body portion (328; 416) extending between the engagement portion and the shielding portion and has an arcuate shape in cross-section, wherein the metal body is configured to form a hoop, split-ring structure with the first end attached to the second end, and wherein the shielding portion (330; 418) is positioned radially inward from the connection. a combustor section having a diffuser case (204; 304; 504) with a diffuser case flange (204a; 304a) and a case support (324, 552); a turbine section arranged aft of the combustor section along an engine central longitudinal axis, the turbine section having turbine case (206; 306; 506) with a turbine case flange (206a; 306a); a connection (202; 302; 502) wherein the diffuser case flange is connected to the turbine case flange; characterized in that: the case support extends radially inward from the diffuser case and extends in an axial direction to provide a forward end engagement; and by a heatshield (322; 400; 522) engaged with the forward end engagement, the heatshield comprising: a metal body having a first end, a second end, a first side, and a second side, wherein the first side and the second side define parallel sides extending from the first end to the second end; an engagement portion (326; 414) formed along the first side and engaging with the forward end engagement of the case support; a shielding portion (330; 418) formed along the second side, wherein an air gap is formed between the heatshield and the connection, with the air gap having an aft extension of the air gap between the shielding portion and the connection, the aft extension extending to an edge of the second side; and a mid-body portion (328; 416) extending between the engagement portion and the shielding portion and has an arcuate shape in cross-section, wherein the metal body is configured to form a hoop, split-ring structure with the first end attached to the second end, and wherein the shielding portion (330; 418) is positioned radially inward from the connection. a metal body having a first end, a second end, a first side, and a second side, wherein the first side and the second side define parallel sides extending from the first end to the second end; an engagement portion (326; 414) formed along the first side and engaging with the forward end engagement of the case support; a shielding portion (330; 418) formed along the second side, wherein an air gap is formed between the heatshield and the connection, with the air gap having an aft extension of the air gap between the shielding portion and the connection, the aft extension extending to an edge of the second side; and a mid-body portion (328; 416) extending between the engagement portion and the shielding portion and has an arcuate shape in cross-section, wherein the metal body is configured to form a hoop, split-ring structure with the first end attached to the second end, and wherein the shielding portion (330; 418) is positioned radially inward from the connection.